aip.scitation.org Open in urlscan Pro
104.18.19.170  Public Scan

Form analysis
2 forms found in the DOM

Name: quickSearch — GET /action/doSearch

<form action="/action/doSearch" name="quickSearch" class="quickSearchForm search-open resQuickSearchForm default-search-container" title="Quick Search" method="get">
  <div class="container">
    <div class="searchNav-tabs">
      <ul class="search-tabs-nav" role="tablist">
        <li id="search-tab" role="presentation" aria-selected="true" aria-controls="search-panel" data-tab-panel="search-panel">
          <a aria-selected="true" tabindex="0" role="tab">SEARCH</a>
        </li>
        <li id="citation-search-tab" role="presentation" aria-selected="false" aria-controls="citation-search-panel" data-tab-panel="citation-search-panel">
          <a aria-hidden="false" tabindex="0" role="tab">CITATION SEARCH</a>
        </li>
        <li id="advance-search-tab" role="presentation" aria-selected="false">
          <a aria-hidden="false" tabindex="0" role="tab" href="/search/advanced">ADVANCED SEARCH</a>
        </li>
      </ul>
    </div>
    <div class="tab-content"> <!-- tab-content open -->
      <div id="search-panel" class="tab-pane active" role="tabpanel" aria-labelledby="search-tab" aria-hidden="false">
        <span class="searchDropDownDivLeft">
          <label for="searchHeaderInSelector" class="visuallyhidden">Search in:</label>
          <select id="searchHeaderInSelector" name="SeriesKey" class="custom-dropdown js__searchInSelector">
            <option value="apl" id="thisJournal" data-search-in="thisJournal"> This Publication </option>
            <option value="false" data-search-in="default">Anywhere</option>
            <option value="" data-search-in="thisPublisher"> This Publisher/Society </option>
          </select>
        </span>
      </div>
      <div id="citation-search-panel" aria-hidden="true" class="tab-pane clear hidden" role="tabpanel" aria-labelledby="citation-search-tab">
        <div class="quicksearch-container">
          <span class="citationSearchBoxContainer hidden">
            <input name="quickLinkJournal" class="journalName mediumTextInput textIndent autocomplete" value="Applied Physics Letters" type="search" title="Journal" placeholder="Journal" autocomplete="off" autopopulate="true"
              data-history-items-conf="3" data-publication-titles-conf="3" data-topics-conf="3" data-contributors-conf="3" data-auto-complete-target="title-auto-complete">
            <input type="hidden" name="quickLink" value="true">
            <input class="year smallTextInput" title="Year" type="search" name="quickLinkYear" value="" autocomplete="false" placeholder="Year" pattern="([0-9]){1,4}$">
            <input class="volume smallTextInput" title="Volume" type="search" name="quickLinkVolume" value="" autocomplete="false" placeholder="Volume" pattern="^[a-zA-Z0-9]+$">
            <input class="issue smallTextInput enable" title="Issue" type="search" name="quickLinkIssue" value="" autocomplete="false" placeholder="Issue" pattern="^[a-zA-Z0-9]+$">
            <input class="page smallTextInput" title="Page" type="search" name="quickLinkPage" value="" autocomplete="false" placeholder="Page" pattern="^[a-zA-Z0-9]+$">
          </span>
          <span class="citationSearchBoxContainer hidden">
            <button class="citation-mainSearchButton">
              <span class="icon-search"></span>
            </button>
          </span>
        </div>
      </div>
    </div> <!-- tab-content Close -->
    <div class="quicksearch-container">
      <div class="simpleSearchBoxContainer">
        <input name="AllField" class="searchText magicsuggest main-search-field textIndent autocomplete" value="" type="search" id="searchText" title="Type search term here" placeholder="Enter words / phrases / DOI / ISBN / authors / keywords / etc."
          autocomplete="off" data-history-items-conf="3" data-publication-titles-conf="3" data-group-titles-conf="3" data-publication-items-conf="3" data-topics-conf="3" data-contributors-conf="3" data-display-labels="true"
          data-fuzzy-suggester="true" data-auto-complete-target="auto-complete">
        <input name="ConceptID" value="" type="hidden">
        <button class="mainSearchButton">
          <span class="sr-only">search</span>
          <span class="icon-search icon-search-btn"></span>
        </button>
      </div>
      <div class="quicksearch-actions">
        <a class="responsiveAdvanceSearch" href="/search/advanced" title="Advanced">
                            <span class="visible-sm visible-xs">
                                Advanced
                            </span>
                            <span class="hidden-xs hidden-sm icon-advanced_search"></span>
                        </a>
      </div>
    </div>
    <div class="cluetips">
      <a class="citationHelp cluetips fancy-tooltip hidden" title="This option allows users to search by Publication, Volume and Page">This option allows users to search by Publication, Volume and Page</a>
      <a class="journalHelp cluetips fancy-tooltip" title="Selecting this option will search the current publication in context.">Selecting this option will search the current publication in context.</a>
      <a class="bookHelp cluetips fancy-tooltip" title="Book Search tips">Book Search tips</a>
      <a class="anywhereHelp cluetips fancy-tooltip hidden" title="Selecting this option will search all publications across the Scitation platform">Selecting this option will search all publications across the Scitation platform</a>
      <a class="thisPublisherHelp cluetips fancy-tooltip hidden" title="Selecting this option will search all publications for the Publisher/Society in context">Selecting this option will search all publications for the Publisher/Society in context</a>
    </div>
  </div>
</form>

POST /action/doLogin

<form action="/action/doLogin" method="post">
  <div class="login-form">
    <input type="hidden" name="id" value="913494f4-bbf3-4bd3-90ce-dec60af6f5ed">
    <input type="hidden" name="redirectUri"
      value="/doi/full/10.1063/5.0081049?Track=&amp;utm_source=AIP+Publishing&amp;utm_medium=email&amp;utm_campaign=13082411_APL_+Piezoelectric+Thin+Films+for+MEMS.+Thermal+Radiation+at+the+Nanoscale+and+Applications_CFP&amp;dm_i=1XPS%2C7SEGB%2C285JYW%2CVRQS2%2C1">
    <input type="hidden" name="popup" value="true">
    <input type="hidden" name="alertPopupLogin" value="true">
    <div class="login-form-inputs">
      <div class="input-group">
        <div class="label ">
          <label for="login">Email</label>
        </div>
        <input id="login" class="login" type="text" name="login" value="" size="15" placeholder="">
        <div class="actions">
        </div>
      </div>
      <div class="input-group">
        <div class="label ">
          <label for="password">Password</label>
        </div>
        <input id="password" class="password" type="password" name="password" value="" autocomplete="off" placeholder="">
        <span class="password-eye-icon icon-eye hidden"></span>
        <div class="actions">
          <a href="/action/requestResetPassword">Forgot password?</a>
        </div>
      </div>
      <div class="remember">
        <div class="keepMeLogin">
          <span class="label">Keep me logged in</span>
        </div>
        <div class="switch small-switch">
          <input id="913494f4-bbf3-4bd3-90ce-dec60af6f5ed-remember" class="cmn-toggle cmn-toggle-round-flat jcf-ignore" title="Keep Me Logged In" type="checkbox" name="remember" value="true">
          <label class="tgl-btn" for="913494f4-bbf3-4bd3-90ce-dec60af6f5ed-remember" title="Keep Me Logged In"></label>
        </div>
      </div>
    </div>
    <div class="footer-buttons">
      <input class="button submit primary" type="submit" name="submit" value="LOGIN">
    </div>
  </div>
</form>

Text Content

MENU
SIGN IN
Sign in/Register

Enter words / phrases / DOI / ISBN / authors / keywords / etc. SEARCH CITATION
SEARCH
 * SEARCH
 * CITATION SEARCH
 * ADVANCED SEARCH

Search in: This Publication Anywhere This Publisher/Society

search
Advanced
This option allows users to search by Publication, Volume and Page Selecting
this option will search the current publication in context. Book Search tips
Selecting this option will search all publications across the Scitation platform
Selecting this option will search all publications for the Publisher/Society in
context



 * Publishers
 * Books
 * Scilight
 * Conference Proceedings
 * Author Resources
 * Librarian Resources
 * Advertiser
 * Contact Us
 * FAQ
 * Help

 * 

 * Publications View All Publications
   * Applied Physics Reviews
   * Applied Physics Letters
   * Journal of Applied Physics
   * The Journal of Chemical Physics
   * Physics Today
   * The Journal of the Acoustical Society of America
   * Review of Scientific Instruments
   * American Journal of Physics
   * Physics of Fluids
   * AIP Advances
   * View All Publications

 * Topics View All Topics
   * Acoustics
   * Biological Physics
   * Condensed Matter Physics
   * Energy
   * Materials Science
   * Mathematical Physics
   * Optics and Optical Physics
   * Physical Chemistry
   * Plasma Physics
   * Rheology and Fluid Dynamics
   * View All Topics



Applied Physics Letters
like and follow us
Facebook
 * Most recent (RSS)
 * Most cited (RSS)

SUBMIT YOUR ARTICLE
 * HOME
   
 * ISSUES
 * MORE
   * INFO
     * Overview
     * Editorial Board
     * News
   * FOR AUTHORS
     * Preparing Your Manuscript
     * Publication Charges
     * Author Resources
     * AIP Author Services
     * Submit
   * COLLECTIONS
     * Editor's Picks
     * Fast Track
     * Featured
     * Perspectives
     * Press Releases
     * Scilights
     * Special Topics
     * Upcoming Special Topics
   
 * ISSUES
 * INFO
   * Overview
   * Editorial Board
   * News
 * FOR AUTHORS
   * Preparing Your Manuscript
   * Publication Charges
   * Author Resources
   * AIP Author Services
   * Submit
 * COLLECTIONS
   * Editor's Picks
   * Fast Track
   * Featured
   * Perspectives
   * Press Releases
   * Scilights
   * Special Topics
   * Upcoming Special Topics

SIGN UP FOR ALERTS


THANK YOU

FOR YOUR INTEREST IN APPLIED PHYSICS LETTERS

To sign up for alerts, please log in first. If you need an account,
please register here

Email

Password
Forgot password?
Keep me logged in



SCALABLE WAYS TO BREAK THE EFFICIENCY LIMIT OF SINGLE-JUNCTION SOLAR CELLS

 * PDF
 * Tools
   * Download Citation
     
   * Add to favorites
   * Reprints and Permissions
 * Share
   E-mail
   Facebook
   Linkedin
   Twitter
   Reddit
   Mendeley
   Recommend to Librarians

 * Home >
 * Applied Physics Letters >
 * Volume 120, Issue 1 >
 * 10.1063/5.0081049

Prev Next


RELATED


ARTICLES

Hydrogenated amorphous silicon oxide (a-SiOx:H) single junction solar cell with
8.8% initial efficiency by reducing parasitic absorptions
Do Yun Kim, Erwin Guijt, René A. C. M. M. van Swaaij and Miro Zeman
more...
The efficiency limit of CH3NH3PbI3 perovskite solar cells
Wei E. I. Sha, Xingang Ren, Luzhou Chen and Wallace C. H. Choy
more...
Enhanced external radiative efficiency for 20.8% efficient single-junction GaInP
solar cells
J. F. Geisz, M. A. Steiner, I. García, S. R. Kurtz and D. J. Friedman
more...
Triple-junction thin-film silicon solar cell fabricated on periodically textured
substrate with a stabilized efficiency of 13.6%
Hitoshi Sai (齋 均 ), Takuya Matsui (松井 卓矢 ), Takashi Koida (鯉田 崇 ), Koji
Matsubara (松原 浩司 ), Michio Kondo (近藤 道雄 ), Shuichiro Sugiyama (杉山 秀一郎 ),
Hirotaka Katayama (片山 博貴 ), Yoshiaki Takeuchi (竹内 良昭 ) and Isao Yoshida (吉田 功 )
more...
Loss analysis for single junction concentrator solar cells
Nicholas J. Ekins-Daukes, Anastasia Soeriyadi, Wenqi Zhao, Stephen Bremner and
Andreas Pusch
more...
Multi-junction solar cells paving the way for super high-efficiency
Masafumi Yamaguchi, Frank Dimroth, John F. Geisz and Nicholas J. Ekins-Daukes
more...
Stabilized 14.0%-efficient triple-junction thin-film silicon solar cell
Hitoshi Sai (齋均 ), Takuya Matsui (松井卓矢 ) and Koji Matsubara (松原浩司 )
more...
Investigation on high-efficiency Ga0.51In0.49P/In0.01Ga0.99As/Ge triple-junction
solar cells for space applications
Lei Zhang, Pingjuan Niu, Yuqiang Li, Minghui Song, Jianxin Zhang, Pingfan Ning
and Peizhuan Chen
more...
Special topic on non-classical light emitters and single-photon detectors
Christoph Becher, Sven Höfling, Jin Liu, Peter Michler, Wolfram Pernice and
Costanza Toninelli
more...
A perspective on conducting domain walls and possibilities for ephemeral
electronics
J. M. Gregg
more...
A perspective on integrated atomo-photonic waveguide circuits
Yuri B. Ovchinnikov
more...
MOCVD growth of MgGa2O4 thin films for high-performance solar-blind UV
photodetectors
Qichao Hou, Kewei Liu, Dongyang Han, Yongxue Zhu, Xing Chen, Binghui Li, Lei Liu
and Dezhen Shen
more...

Free Submitted: 06 December 2021 Accepted: 06 December 2021 Published Online: 04
January 2022
 * SCALABLE WAYS TO BREAK THE EFFICIENCY LIMIT OF SINGLE-JUNCTION SOLAR CELLS
 * 


Appl. Phys. Lett. 120, 010402 (2022); https://doi.org/10.1063/5.0081049
Bruno Ehrler1,a), Anita W. Y. Ho-Baillie2, Eline M. Hutter3, Jovana V. Milić4,
Murad J. Y. Tayebjee5, and Mark W. B. Wilson6
more...View Affiliations
 * 1AMOLF, Center for Nanophotonics, Science Park 104, 1098 XG Amsterdam, The
   Netherlands
 * 2School of Physics and Sydney Nano Institute, The University of Sydney,
   Sydney, NSW 2006, Australia
 * 3Inorganic Chemistry and Catalysis, Princetonlaan 8, 3584 CB Utrecht, The
   Netherlands
 * 4Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4,
   CH-1700 Fribourg, Switzerland
 * 5School of Photovoltaic and Renewable Engineering, UNSW Sydney, Kensington
   2052, Australia
 * 6Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6,
   Canada
 * a)Author to whom correspondence should be addressed: ehrler@amolf.nl

   Note: This paper is part of the APL Special Collection on Scalable Ways to
   Break the Efficiency Limit of Single-Junction Solar Cells.

View Contributors
 * Bruno Ehrler
 * Anita W. Y. Ho-Baillie
 * Eline M. Hutter
 * Jovana V. Milić
 * Murad J. Y. Tayebjee
 * Mark W. B. Wilson




 * PDF
   
   
 * CHORUS

 * First Page
 * Full Text
 * Figures
 * Tools
   * Download Citation
   * Add to Favorites
   * Reprints and Permissions
 * E-mail
   Facebook
   Linkedin
   Twitter
   Reddit
   Mendeley
   Recommend to Librarian
 * 

Share
E-mail
Facebook
Linkedin
Twitter
Reddit
Mendeley
Recommend to Librarian
metrics


2.7K

Views


 * Topics
   * Special Topics
     * Scalable Ways to Break the Efficiency Limit of Single-Junction Solar
       Cells
   * Topics
     * Thin films
     * Solar cells
     * Photoluminescence spectroscopy
     * Heterostructures
     * Electronic transport
     * Excitons
     * Recombination reactions
     * Photovoltaics
     * Perovskites

Solar photovoltaics will play a dominant role in the power generation of the
zero-carbon future.11. Energy Watch Group, Global Energy System Based on 100%
Renewable Energy ( Energy Watch Group, 2019). Today, the market of large-scale
solar power generation is dominated by silicon solar cells, where
high-performance lab-scale devices are reaching their detailed-balance
efficiency limit.22. B. Ehrler, E. Alarcón-Lladó, S. W. Tabernig, T. Veeken, E.
C. Garnett, and A. Polman, ACS Energy Lett. 5, 3029 (2020).
https://doi.org/10.1021/acsenergylett.0c01790 With decreasing module prices,33.
M. A. Green, Joule 3, 631 (2019). https://doi.org/10.1016/j.joule.2019.02.010
cell efficiency becomes more valuable as it becomes an increasingly important
driver for further reductions in the levelized cost of electricity.
The next generation of solar cells thus strives to surpass the efficiency limit
of single-junction solar cells. Multi-junction solar cells, such as those based
on III–V materials, are already very efficient, yet these materials have
remained prohibitively expensive for large-scale deployment.44. A. Polman, M.
Knight, E. C. Garnett, B. Ehrler, and W. C. Sinke, Science 352, 307 (2016).
https://doi.org/10.1126/science.aad4424 In this special topic, we instead focus
on nascent techniques and materials that offer the possibility to exceed the
single-junction efficiency limit in a scalable (multi-km2) way in the future.
The detailed-balance single-junction efficiency limit assumes that the solar
cell consists of a single absorber layer, in which an incoming photon generates
a single electron–hole pair that can be extracted to perform work.55. W.
Shockley and H. J. Queisser, J. Appl. Phys. 32, 510 (1961).
https://doi.org/10.1063/1.1736034 All common schemes that go beyond this limit
break at least one of these assumptions: they use two or more absorber layers
with different optical bandgaps or enable the generation of more than a single
electron–hole pair, so that the broad solar spectrum can be used more
efficiently. Broadly speaking, the resulting solar cells discussed in this
special topic collection can be categorized into two main categories, namely,
tandem solar cells and solar cells that make use of up- or downconversion (Fig.
1). Here, we bring together reports on scalable ways to overcome the limitations
of single-junction solar cells using these approaches.
FIG. 1. Working principle of a tandem solar cell (left) and an up- and
downconversion-based solar cell (right). The tandem cell consists of two
separate sub-cells, often the bottom cell is made of silicon and absorbs the
low-energy part of the solar spectrum, and the top cell absorbs the
higher-energy photons. The up- and downconversion cell often only consists of
one solar cell junction, while the up- and downconversion layers transform the
incident spectrum so that it can be better converted by the cell.
   
 * PPT
   |
 * High resolution

A tandem solar cell consists of two individual sub-cells, each having its own
bandgap and its own junction to aid electron-hole separation.66. S. M. Bedair,
M. F. Lamorte, and J. R. Hauser, Appl. Phys. Lett. 34, 38 (1979).
https://doi.org/10.1063/1.90576 There are different ways to connect the two
sub-cells. For instance, they can be electrically independent and only optically
connected (four-terminal cell, 4T), permitting the independent power developed
by each cell to be combined externally. Alternatively, they can be connected
electrically in series (two-terminal cell, 2T), where the voltages intrinsically
sum, but the current needs to be matched. Other geometries, such as
three-terminal cells, are less common. Tandem cells could be highly relevant in
the fast deployment of solar PV in the near future.
Solar PV technologies target the generation of electricity without the emission
of significant greenhouse gasses; but to reach the goals of the Paris
Agreement,77. J. Rogelj, D. Shindell, K. Jiang, S. Fifita, et al., “ Mitigation
pathways compatible with 1.5 °C in the context of sustainable development”
(published online 2018). the transition toward this low-carbon generation of
electricity must be rapid.88. P. Friedlingstein, M. O'Sullivan, M. W. Jones, R.
M. Andrew, J. Hauck, A. Olsen, G. P. Peters, W. Peters, J. Pongratz, S. Sitch,
C. L. Quéré, J. G. Canadell, P. Ciais, R. B. Jackson, S. Alin, L. E. O. C.
Aragão, A. Arneth, V. Arora, N. R. Bates, M. Becker, A. Benoit-Cattin, H. C.
Bittig, L. Bopp, S. Bultan, N. Chandra, F. Chevallier, L. P. Chini, W. Evans, L.
Florentie, P. M. Forster, T. Gasser, M. Gehlen, D. Gilfillan, T. Gkritzalis, L.
Gregor, N. Gruber, I. Harris, K. Hartung, V. Haverd, R. A. Houghton, T. Ilyina,
A. K. Jain, E. Joetzjer, K. Kadono, E. Kato, V. Kitidis, J. I. Korsbakken, P.
Landschützer, N. Lefèvre, A. Lenton, S. Lienert, Z. Liu, D. Lombardozzi, G.
Marland, N. Metzl, D. R. Munro, J. E. M. S. Nabel, S. I. Nakaoka, Y. Niwa, K.
O'Brien, T. Ono, P. I. Palmer, D. Pierrot, B. Poulter, L. Resplandy, E.
Robertson, C. Rödenbeck, J. Schwinger, R. Séférian, I. Skjelvan, A. J. P. Smith,
A. J. Sutton, T. Tanhua, P. P. Tans, H. Tian, B. Tilbrook, G. Van Der Werf, N.
Vuichard, A. P. Walker, R. Wanninkhof, A. J. Watson, D. Willis, A. J. Wiltshire,
W. Yuan, X. Yue, and S. Zaehle, Earth Syst. Sci. Data 12, 3269 (2020).
https://doi.org/10.5194/essd-12-3269-2020 This gives a deployment advantage to
new technologies that are compatible with existing technologies, production
facilities, and markets. Kamaraki et al. show that perovskite/silicon tandem
solar cells fulfill many of these requirements.99. C. Kamaraki, M. T. Klug, T.
Green, L. Miranda Perez, and C. Case, Appl. Phys. Lett. 119, 070501 (2021).
https://doi.org/10.1063/5.0054086 The authors work for the company Oxford PV,
which is commercializing the technology. They claim that the most commercially
viable tandem cell is a 2T configuration, because the 4T cells would require
doubling the number of inverters, which is cost-prohibitive in the current
market. Si solar cells are chosen as the most promising bottom cell because of
their current dominance, proven long-lasting performance, and low cost. For the
top cell, it is not enough to be efficient or low-cost, but the cell must be
both—particularly of comparable efficiency to the bottom cell. Thus, they
describe how a metal halide perovskite top cell potentially fulfills these
requirements since high-quality films can be formed by a variety of simple,
low-cost deposition techniques. In addition, the technological compatibility of
perovskite cells with the existing and highly developed Si industry allows these
tandems to leverage the decades of development in Si cells and module
fabrication, as well as systems and business development. An important
commercial consideration is that perovskite/Si tandem modules offer a higher
efficiency than traditional Si-only modules, which allows the producer to charge
a premium in applications where space is limited such as in rooftop systems.
After market introduction, they emphasize that the learning curve of the tandem
cells needs to keep pace with Si-only cells to remain competitive. They are
optimistic that large efficiency potential and the connection to the
established, large-scale Si industry should make this possible.
There are still several materials challenges to overcome before perovskite-based
tandem cells become a reality. Several of these are addressed in this special
topic collection. A high photoluminescence quantum yield (PLQY) is critical for
all solar cell materials. Perovskites often show high PLQY, but it can be
diminished by sample morphology and material purity. Screening material
compositions and fabrication techniques, therefore, requires a rapid method to
study the PLQY of a perovskite sample. Akhundova et al. show that the spectral
shape of the photoluminescence (PL) from wide-bandgap perovskites correlates
with the PLQY of a sample.1010. F. Akhundova, L. Lüer, A. Osvet, J. Hauch, I. M.
Peters, K. Forberich, N. Li, and C. Brabec, Appl. Phys. Lett. 118, 243903
(2021). https://doi.org/10.1063/5.0049010 The authors assign this correlation to
the observation both the PLQY and the spectral shape reflect the domain size
dispersion because of its role in the funneling of carriers into trap sites. The
size dispersion is greatly affected by processing parameters such as annealing
conditions, and these results highlight the importance of carefully controlling
fabrication.
The fabrication of perovskite thin films needs to be scalable without
compromising luminescence efficiency. Ishteev et al. demonstrate a new
deposition technique for all-inorganic, large-bandgap perovskite thin
films.1111. A. Ishteev, L. Luchnikov, D. S. Muratov, M. Voronova, A. Forde, T.
Inerbaev, V. Vanyushin, D. Saranin, K. Yusupov, D. Kuznetsov, and A. Di Carlo,
Appl. Phys. Lett. 119, 071901 (2021). https://doi.org/10.1063/5.0055993 They
fabricate the precursors, CsBr and PbBr2, by dry, mechanical milling before
deposition in a single-source CVD process under mild vacuum (0.02–1.00 mBar).
All these techniques are, in principle, scalable, and the authors are able to
vary the ratio between the precursors (i.e., CsBr:PbBr2) to search for the most
luminescent composition. They observe greatest brightness from a 35:65 ratio, a
composition that forms both the CsPb2Br5 and CsPbBr3 perovskites. They
demonstrate that this technique can be used to conformally coat textured
surfaces but identify that the stability and PLQY will require further
improvements.
For the full device stack, perovskite tandem cells require transparent
electrodes (4T) and interconnection layers (2T). These layers have received
considerable attention because of their importance for the overall performance.
The interconnection layer between the two subcells of a 2T tandem cell ideally
offers good recombination properties, while transmitting all low-energy light.
Koç et al. calculate the optical transmission of an interconnection layer
consisting of thin Ag between two transport layers in a perovskite-perovskite
tandem cell.1212. M. Koc, M. Ameri, and S. Yerci, Appl. Phys. Lett. 119, 021102
(2021). https://doi.org/10.1063/5.0048780 They report transfer matrix
calculations that explore the transmission of light into the low-bandgap bottom
cell when the thicknesses of the silver layer and the adjacent transport layers
are varied. They find two tradeoffs. First, the refractive index of the transfer
layers is important to the transmission of light. Ideally, the index would be
larger than 1.9; however, by the Kramers–Kronig relationship, these high indices
will also lead to larger parasitic absorption. Second, the silver layer should
be as thin as possible for good light transmission (even 3 nm already reduces
the photocurrent from the bottom cell), but thicker layers lead to larger
lateral conductivity.
For 4T tandem cells, the top cell needs to be fully transparent to below-bandgap
light. However, the transparent conductive electrode required induces large
parasitic absorption and often used indium-tin oxide (ITO) is too brittle to be
implemented in flexible solar cells. As in the previous example for
interconnection layers, thin metal layers can also perform as excellent
transparent conductive electrodes. Spinelli et al. sandwich a sputtered layer of
Ag or co-sputtered Ag/Cu between two layers of ITO, and these ITO-Cu/Ag-ITO
electrodes show a NIR transmission similar to ITO when the layer thicknesses are
optimized.1313. P. Spinelli, R. Fuentes Pineda, M. Scigaj, T. Ahmad, and K.
Wojciechowski, Appl. Phys. Lett. 118, 241110 (2021).
https://doi.org/10.1063/5.0052209 They perform this using transfer-matrix
modeling, identifying an optimal transmission for thicknesses of 40 nm for the
first ITO layer, 5 nm for the metal, and 65 nm for the second ITO layer. The
layers were then processed in a full device stack with a large-bandgap
perovskite as the active layer and performed slightly better than the same
device with an ITO contact. In addition, they find that the initial sheet
resistance of the ITO-metal-ITO contact is about half that of pure ITO (200 nm),
and it retains this value upon repeated bending cycles, while the ITO resistance
doubles after about 1000 cycles. The authors work for Saule Technologies, a
company commercializing perovskite solar cell products, and they are confident
that this contact architecture can provide a scalable and efficient solution for
applications.
While perovskite/silicon and perovskite/perovskite tandem cells receive
significant attention from the research community because of their potential for
implementation at scale in large-area photovoltaics, different tandem
configurations offer interesting properties for other applications. For example,
III–V semiconductor/Si tandem solar cells combine a low-cost and
well-established Si bottom cell with a highly efficient III–V top cell. While
too expensive for large-area applications, these cells might suit the
high-performance end of the market, for example, for vehicle-integrated PV.
Whitehead et al. fabricate a 4T GaAs/Si tandem cell that is mechanically stacked
by combining various thicknesses of GaAs with a Si cell that features
interdigitated back contacts.1414. R. C. Whitehead, K. T. VanSant, E. L. Warren,
J. Buencuerpo, M. Rienäcker, R. Peibst, J. F. Geisz, and A. C. Tamboli, Appl.
Phys. Lett. 118, 183902 (2021). https://doi.org/10.1063/5.0049097 The 4T
configuration is necessary here, because the bandgap of GaAs is too low for a
current-matched 2T combination with Si. The back-contacted silicon cell makes
the stacking and contacting easier. The authors find that the tandem cell
efficiency does not depend too heavily on the GaAs thickness as long as it is
thicker than 1.9 μm. All tandem cells show excellent performance with >30% power
conversion efficiency, and their cell with 2.8 μm GaAs shows the highest tandem
efficiency (32.57%). The performance for the various layer thicknesses is
confirmed with transfer matrix modeling for the optical transmission and
absorption, Lambertian light-trapping for the Si cell, and the Hovel method to
study the effect of photon recycling. The low refractive index of the glass
interlayer ensures that the GaAs cell benefits from the effect of photon
recycling by trapping the emitted light inside the top cell.
Like tandem solar cells, two or more effective bandgaps are also required for
the up- and downconversion schemes. However, only one of them needs to form a
semiconductor junction to extract charge. The other bandgap can then be used to
down-convert the energy if the bandgap is higher than the one that forms the
junction or upconvert if it is lower. There are several mechanisms for both up-
and downconversion. In this special topic collection, we find contributions on
singlet fission and multiple exciton generation as downconversion processes, and
triplet–triplet annihilation and intermediate-gap solar cells as upconversion
processes.
Singlet fission is a process that can be used in photon downconversion, and the
most thoroughly studied materials are crystalline, conjugated small molecules
such as the linear acenes. Photon absorption in these materials initially
generates spin-singlet excitons. These are converted by fission into pairs of
lower-energy spin-correlated triplet excitons.1515. M. B. Smith and J. Michl,
Chem. Rev. 110, 6891 (2010). https://doi.org/10.1021/cr1002613 The process is
spin-allowed and is, hence, can be rapid and efficient in materials where it is
energetically favorable.1616. M. W. B. Wilson, A. Rao, B. Ehrler, and R. H.
Friend, Acc. Chem. Res. 46, 1330 (2013). https://doi.org/10.1021/ar300345h In
that respect, singlet fission appears to be an ideal downconversion mechanism
when combined with a low-bandgap solar cell. In practice, however, multiple
challenges arise when implementing these organic materials in a practical solar
cell architecture. Cheung and Kaake investigate the effect of the exciton
binding energy and endothermicity on the potential solar cell efficiency.1717.
J. C. F. Cheung and L. G. Kaake, Appl. Phys. Lett. 119, 013301 (2021).
https://doi.org/10.1063/5.0047964 The binding energy comes from the Coulombic
interaction between the electron and hole of the exciton. The endothermicity,
also called entropic gain, is observed in many singlet fission materials and
stems from the greater number of microstates possible when one singlet exciton
converts into two triplet excitons.1818. N. V. Korovina, C. H. Chang, and J. C.
Johnson, Nat. Chem. 12, 391 (2020). https://doi.org/10.1038/s41557-020-0422-7
The authors use both the optical gaps of the singlet fission material and the
low-bandgap solar cell as free parameters in a detailed-balance based efficiency
calculation and assume charge transfer from the triplet exciton to generate
current. They find that in simple two-bandgap systems, the efficiency drop from
the exciton binding energy can be partially recovered by the endothermicity.
However, at high exciton binding energies (e.g., 0.5 eV), the maximum achievable
efficiency drops from 43.9% to 31.0% even assuming an effective endothermicity
of 0.25 eV. Then, a double heterojunction is introduced with a bridge molecule
that serves to accept electrons from the triplet excitons, much like in ternary
blend organic solar cells.1919. W. Xu and F. Gao, Mater. Horiz. 5, 206 (2018).
https://doi.org/10.1039/C7MH00958E This bridge molecule reduces recombination
and aids charge separation. The result is that the maximum achievable solar cell
performance remains high even at high exciton binding energies. Revisiting the
example mentioned previously, with 0.5 eV exciton binding energy and 0.25 eV
endothermicity, they show that the bridge molecules would lift the efficiency
potential from 31.0% to well above 40%. While charge separation from singlet
fission-generated triplet excitons may lead to high efficiency,2020. B. Daiber,
K. Van Den Hoven, M. H. Futscher, and B. Ehrler, ACS Energy Lett. 6, 2800
(2021). https://doi.org/10.1021/acsenergylett.1c00972 the most promising
experimental realizations with singlet fission and silicon cells so far rely on
energy transfer.2121. M. Einzinger, T. Wu, J. F. Kompalla, H. L. Smith, C. F.
Perkinson, L. Nienhaus, S. Wieghold, D. N. Congreve, A. Kahn, M. G. Bawendi, and
M. A. Baldo, Nature 571, 90–94 (2019). https://doi.org/10.1038/s41586-019-1339-4
Many downconversion processes are technically multiple-exciton generation
processes, but conventionally the term multiple exciton generation (MEG) refers
to the inverse Auger process in inorganic semiconductors that generates two or
more band edge electron–hole pairs from one high-energy photoexcitation. This
process is inefficient in bulk materials both energetically and in terms of
quantum yield, but prospects are improved in colloidal quantum dots due to
factors that include improved momentum matching.2222. J. Gao, A. F. Fidler, and
V. I. Klimov, Nat. Commun. 6, 8185 (2015). https://doi.org/10.1038/ncomms9185
Solar cells utilizing MEG to achieve greater-than-unity photon-to-carrier yield
at select wavelengths have been demonstrated2323. O. E. Semonin, J. M. Luther,
S. Choi, H.-Y. Chen, J. Gao, A. J. Nozik, and M. C. Beard, Science 334, 1530
(2011). https://doi.org/10.1126/science.1209845 but have not yet reached high
energy-conversion efficiencies. Writing in this collection, Pusch et al. show
that equilibrium-only models are insufficient in assessing the efficiency
potential of such cells, because of the voltage dependence of the inverse
process of MEG, Auger recombination.2424. A. Pusch, S. P. Bremner, M. J. Y.
Tayebjee, and N. J. E. Daukes, Appl. Phys. Lett. 118, 151103 (2021).
https://doi.org/10.1063/5.0049120 As voltage increases, Auger recombination
starts to play a larger role. In contrast, all relevant processes in
conventional solar cells are well separated in time. In these conventional
cases, the external quantum efficiency measured at short circuit can be used to
calculate the photocurrent, and the superposition principle applies. However,
when the efficiency potential of MEG solar cells is assessed, microscopic
reversibility must be explicitly considered to properly treat the interplay
between MEG and Auger recombination. Pusch et al. devise a model that
incorporates these considerations for a quantum dot-based device assuming
equidistant, discrete energy levels. This model reproduces experimentally
observed EQE curves, and they show that the quasi-Fermi level splitting varies
across the device due to the microscopic reversibility. The MEG process, thus,
depends on the applied voltage, and as a result, the calculated IV curves show a
lower open-circuit voltage compared to a model that assumes equilibrium
conditions. Inclusion of trion states to the Auger recombination rate further
reduces the efficiency potential, so preventing these charged states in devices
will be critical to achieve significant efficiency gains over single-junction
solar cells.
MEG and singlet fission both harness high-energy photons to generate multiple
excitons of lower energy. In principle, direct extraction of the energy of hot
carriers is also possible. There are major challenges, however, which are in
part related to the generally rapid relaxation of hot carriers to the band edge.
Esmaielpour et al. investigate the hot-carrier relaxation in type-II InAs/AlAsSb
multi-quantum well structures.2525. H. Esmaielpour, B. K. Durant, K. R. Dorman,
V. R. Whiteside, J. Garg, T. D. Mishima, M. B. Santos, I. R. Sellers, J. F.
Guillemoles, and D. Suchet, Appl. Phys. Lett. 118, 213902 (2021).
https://doi.org/10.1063/5.0052600 They study the effect of different barrier
thicknesses on hot carrier relaxation by measuring the PL spectrum at different
excitation intensities. By measuring the excess temperature from the PL spectrum
for different barrier layer thicknesses, they find that the barrier layer
thickness has an effect of the effective temperature because of changes in the
cooling rates. The authors explain this difference by a difference in phonon
scattering rates. Supported by DFT calculations, they find that the larger
barrier layers (higher InAs/AlSb ratio) show a reduced phonon density of states,
which leads to an increase in the phonon scattering time.
While all the previous examples aim to make better use of the high-energy part
of the solar spectrum, upconversion does the opposite. In such schemes,
below-bandgap photons are absorbed in an upconverter material and transformed
into higher-energy photons or excitations. An attractive strategy for incoherent
photon upconversion efficiencies is based on triplet-triplet annihilation (TTA),
also known as triplet fusion, where pairs of spin-triplet excitons are combined
to form a higher-energy, emissive spin-singlet exciton. The most efficient
schemes have relied on external sensitizers that absorb incident light and then
transfer this energy to annihilator/emitter molecules. Traditionally, these
schemes relied on metal-organic complexes to serve as sensitizers,2626. T. N.
Singh-Rachford and F. N. Castellano, Coord. Chem. Rev. 254, 2560 (2010).
https://doi.org/10.1016/j.ccr.2010.01.003 and more recently colloidal quantum
dots27,2827. Z. Huang, X. Li, M. Mahboub, K. M. Hanson, V. M. Nichols, H. Le, M.
L. Tang, and C. J. Bardeen, Nano Lett. 15, 5552 (2015).
https://doi.org/10.1021/acs.nanolett.5b0213028. M. Wu, D. N. Congreve, M. W. B.
Wilson, J. Jean, N. Geva, M. Welborn, T. Van Voorhis, V. Bulovi, M. G. Bawendi,
and M. A. Baldo, Nat. Photonics 10, 31 (2016).
https://doi.org/10.1038/nphoton.2015.226 and lanthanide-doped nanoparticles
sensitizers combined with organic emitters.2929. S. Han, R. Deng, Q. Gu, L. Ni,
U. Huynh, J. Zhang, Z. Yi, B. Zhao, H. Tamura, A. Pershin, H. Xu, Z. Huang, S.
Ahmad, M. Abdi-Jalebi, A. Sadhanala, M. L. Tang, A. Bakulin, D. Beljonne, X.
Liu, and A. Rao, Nature 587, 594 (2020).
https://doi.org/10.1038/s41586-020-2932-2 With the rise of perovskites as the
dominant thin-film semiconductor (at least in the research community),
perovskite nanocrystals3030. X. Luo, Y. Han, Z. Chen, Y. Li, G. Liang, X. Liu,
T. Ding, C. Nie, M. Wang, F. N. Castellano, and K. Wu, Nat. Commun. 11, 28
(2020). https://doi.org/10.1038/s41467-019-13951-3 and films3131. L. Nienhaus,
J. P. Correa-Baena, S. Wieghold, M. Einzinger, T. A. Lin, K. E. Shulenberger, N.
D. Klein, M. Wu, V. Bulović, T. Buonassisi, M. A. Baldo, and M. G. Bawendi, ACS
Energy Lett. 4, 888 (2019). https://doi.org/10.1021/acsenergylett.9b00283 have
also now been used as sensitizers for TTA upconversion. Surprisingly, even bulk
perovskites performed very efficiently thanks to their high charge carrier
mobility and long charge carrier lifetimes. For applications in solar cells,
these upconversion systems need to work efficiently at sub-solar fluxes and
under continuous illumination. Writing in this collection, Vanorman et al. study
the effect of illumination on the efficiency of a (MAFA)PbI3 perovskite/rubrene
upconversion bilayer.3232. Z. A. Vanorman, J. Lackner, S. Wieghold, K. Nienhaus,
G. U. Nienhaus, and L. Nienhaus, Appl. Phys. Lett. 118, 203903 (2021).
https://doi.org/10.1063/5.0050185 They show that the continued illumination
improves the upconversion efficiency, which correlates with an increase in the
total perovskite PL that is associated with the relative suppression of
short-lifetime decay channels. This is consistent with trap filling within the
perovskite layer, because populating the triplet excitons in rubrene by the
perovskite excitations competes with trapping within the perovskite and at the
interface. Under continued illumination, they observe that the upconversion PL
from rubrene rises more rapidly following additional pulsed excitation,
providing further evidence that the transfer of energy into the rubrene triplet
state is improved. The works highlights that the upconversion efficiency
reported in these systems strongly depends on not only the incident power but
also the illumination history of the sample.
A theoretically elegant but technically challenging way to overcome the
efficiency limit of single-junction solar cells is the concept of
intermediate-gap solar cells.33,3433. A. Luque and A. Martí, Phys. Rev. Lett.
78, 5014 (1997). https://doi.org/10.1103/PhysRevLett.78.501434. Y. Okada, N. J.
Ekins-Daukes, T. Kita, R. Tamaki, M. Yoshida, A. Pusch, O. Hess, C. C. Phillips,
D. J. Farrell, K. Yoshida, N. Ahsan, Y. Shoji, T. Sogabe, and J. F. Guillemoles,
Appl. Phys. Rev. 2, 021302 (2015). https://doi.org/10.1063/1.4916561 Here, a
state within the bandgap of the absorber layer is used to provide a second
absorption gap. The intrinsic challenge in this architecture is that the
reciprocity of absorption and emission processes mean that charges in the
intermediate gap typically recombine faster than photons can be absorbed at
solar flux to generate excitations across the bandgap. This issue can be
overcome by “parking” electrons in a second level slightly lower than the
intermediate gap to prolong their lifetime. Huang et al. investigate
theoretically such a system where a bilayer of Sn-doped AgAlTe2 and LiInTe2 is
also used to aid charge separation in a type-II heterojunction.3535. D. Huang,
L. Ding, Y. Xue, J. Guo, Y. J. Zhao, and C. Persson, Appl. Phys. Lett. 118,
043901 (2021). https://doi.org/10.1063/5.0034852 They calculate the band
structure of both pure materials and those doped with various group-IV metals.
The combination of the Sn-doped materials provides good lattice matching and
maintains the type-II heterojunctions of the undoped materials.
Overall, this special topic collection shows the breadth of studies, the
novelty, and the creativity that the research community is applying to
circumvent the single-junction efficiency limit for solar cells. While some
concepts, such as perovskite/silicon tandems, are close to market entry, others,
while demonstrated, are not yet commercially viable for large-scale terrestrial
applications, such as the III–V based technologies. The up- and downconversion
technologies, on the other hand, have enormous potential both for high
efficiency and for low cost but are further away from commercial implementation.
We embrace this wide range of technologies at different stages of research, and
we see a bright future for high-efficiency, large-scale solar cell applications.
We would like to thank all the authors that have contributed and the editors of
APL Maria Antonietta Loi and Lesley Cohen as well as Emma Nicholson van Burns
and Jessica Trudeau for their assistance.
The work of B.E. was part of the Dutch Research Council (NWO) and was performed
at the research institute AMOLF. The work of J.V.M. is part of the Swiss
National Science Foundation (SNSF) PRIMA project performed at the Adolphe Merkle
Institute. A.H.-B. would like to acknowledge the support of the Australian
Government through the Australian Research Council Future Fellowship (No.
FT210100210) and through Australian Renewable Energy Agency (ARENA)-2020/RND001
and 2020/RND003 projects.
DATA AVAILABILITY

Data sharing is not applicable to this article as no new data were created or
analyzed in this study.

REFERENCES

 1.  1. Energy Watch Group, Global Energy System Based on 100% Renewable Energy
     ( Energy Watch Group, 2019). Google Scholar
 2.  2. B. Ehrler, E. Alarcón-Lladó, S. W. Tabernig, T. Veeken, E. C. Garnett,
     and A. Polman, ACS Energy Lett. 5, 3029 (2020).
     https://doi.org/10.1021/acsenergylett.0c01790, Google ScholarCrossref
 3.  3. M. A. Green, Joule 3, 631 (2019).
     https://doi.org/10.1016/j.joule.2019.02.010, Google ScholarCrossref
 4.  4. A. Polman, M. Knight, E. C. Garnett, B. Ehrler, and W. C. Sinke, Science
     352, 307 (2016). https://doi.org/10.1126/science.aad4424, Google
     ScholarCrossref
 5.  5. W. Shockley and H. J. Queisser, J. Appl. Phys. 32, 510 (1961).
     https://doi.org/10.1063/1.1736034, Google ScholarScitation, ISI
 6.  6. S. M. Bedair, M. F. Lamorte, and J. R. Hauser, Appl. Phys. Lett. 34, 38
     (1979). https://doi.org/10.1063/1.90576, Google ScholarScitation, ISI
 7.  7. J. Rogelj, D. Shindell, K. Jiang, S. Fifita, et al., “ Mitigation
     pathways compatible with 1.5 °C in the context of sustainable development”
     (published online 2018). Google Scholar
 8.  8. P. Friedlingstein, M. O'Sullivan, M. W. Jones, R. M. Andrew, J. Hauck,
     A. Olsen, G. P. Peters, W. Peters, J. Pongratz, S. Sitch, C. L. Quéré, J.
     G. Canadell, P. Ciais, R. B. Jackson, S. Alin, L. E. O. C. Aragão, A.
     Arneth, V. Arora, N. R. Bates, M. Becker, A. Benoit-Cattin, H. C. Bittig,
     L. Bopp, S. Bultan, N. Chandra, F. Chevallier, L. P. Chini, W. Evans, L.
     Florentie, P. M. Forster, T. Gasser, M. Gehlen, D. Gilfillan, T.
     Gkritzalis, L. Gregor, N. Gruber, I. Harris, K. Hartung, V. Haverd, R. A.
     Houghton, T. Ilyina, A. K. Jain, E. Joetzjer, K. Kadono, E. Kato, V.
     Kitidis, J. I. Korsbakken, P. Landschützer, N. Lefèvre, A. Lenton, S.
     Lienert, Z. Liu, D. Lombardozzi, G. Marland, N. Metzl, D. R. Munro, J. E.
     M. S. Nabel, S. I. Nakaoka, Y. Niwa, K. O'Brien, T. Ono, P. I. Palmer, D.
     Pierrot, B. Poulter, L. Resplandy, E. Robertson, C. Rödenbeck, J.
     Schwinger, R. Séférian, I. Skjelvan, A. J. P. Smith, A. J. Sutton, T.
     Tanhua, P. P. Tans, H. Tian, B. Tilbrook, G. Van Der Werf, N. Vuichard, A.
     P. Walker, R. Wanninkhof, A. J. Watson, D. Willis, A. J. Wiltshire, W.
     Yuan, X. Yue, and S. Zaehle, Earth Syst. Sci. Data 12, 3269 (2020).
     https://doi.org/10.5194/essd-12-3269-2020, Google ScholarCrossref
 9.  9. C. Kamaraki, M. T. Klug, T. Green, L. Miranda Perez, and C. Case, Appl.
     Phys. Lett. 119, 070501 (2021). https://doi.org/10.1063/5.0054086, Google
     ScholarScitation
 10. 10. F. Akhundova, L. Lüer, A. Osvet, J. Hauch, I. M. Peters, K. Forberich,
     N. Li, and C. Brabec, Appl. Phys. Lett. 118, 243903 (2021).
     https://doi.org/10.1063/5.0049010, Google ScholarScitation
 11. 11. A. Ishteev, L. Luchnikov, D. S. Muratov, M. Voronova, A. Forde, T.
     Inerbaev, V. Vanyushin, D. Saranin, K. Yusupov, D. Kuznetsov, and A. Di
     Carlo, Appl. Phys. Lett. 119, 071901 (2021).
     https://doi.org/10.1063/5.0055993, Google ScholarScitation
 12. 12. M. Koc, M. Ameri, and S. Yerci, Appl. Phys. Lett. 119, 021102 (2021).
     https://doi.org/10.1063/5.0048780, Google ScholarScitation
 13. 13. P. Spinelli, R. Fuentes Pineda, M. Scigaj, T. Ahmad, and K.
     Wojciechowski, Appl. Phys. Lett. 118, 241110 (2021).
     https://doi.org/10.1063/5.0052209, Google ScholarScitation
 14. 14. R. C. Whitehead, K. T. VanSant, E. L. Warren, J. Buencuerpo, M.
     Rienäcker, R. Peibst, J. F. Geisz, and A. C. Tamboli, Appl. Phys. Lett.
     118, 183902 (2021). https://doi.org/10.1063/5.0049097, Google
     ScholarScitation
 15. 15. M. B. Smith and J. Michl, Chem. Rev. 110, 6891 (2010).
     https://doi.org/10.1021/cr1002613, Google ScholarCrossref, ISI
 16. 16. M. W. B. Wilson, A. Rao, B. Ehrler, and R. H. Friend, Acc. Chem. Res.
     46, 1330 (2013). https://doi.org/10.1021/ar300345h, Google ScholarCrossref,
     ISI
 17. 17. J. C. F. Cheung and L. G. Kaake, Appl. Phys. Lett. 119, 013301 (2021).
     https://doi.org/10.1063/5.0047964, Google ScholarScitation, ISI
 18. 18. N. V. Korovina, C. H. Chang, and J. C. Johnson, Nat. Chem. 12, 391
     (2020). https://doi.org/10.1038/s41557-020-0422-7, Google ScholarCrossref
 19. 19. W. Xu and F. Gao, Mater. Horiz. 5, 206 (2018).
     https://doi.org/10.1039/C7MH00958E, Google ScholarCrossref
 20. 20. B. Daiber, K. Van Den Hoven, M. H. Futscher, and B. Ehrler, ACS Energy
     Lett. 6, 2800 (2021). https://doi.org/10.1021/acsenergylett.1c00972, Google
     ScholarCrossref
 21. 21. M. Einzinger, T. Wu, J. F. Kompalla, H. L. Smith, C. F. Perkinson, L.
     Nienhaus, S. Wieghold, D. N. Congreve, A. Kahn, M. G. Bawendi, and M. A.
     Baldo, Nature 571, 90–94 (2019). https://doi.org/10.1038/s41586-019-1339-4,
     Google ScholarCrossref, ISI
 22. 22. J. Gao, A. F. Fidler, and V. I. Klimov, Nat. Commun. 6, 8185 (2015).
     https://doi.org/10.1038/ncomms9185, Google ScholarCrossref
 23. 23. O. E. Semonin, J. M. Luther, S. Choi, H.-Y. Chen, J. Gao, A. J. Nozik,
     and M. C. Beard, Science 334, 1530 (2011).
     https://doi.org/10.1126/science.1209845, Google ScholarCrossref
 24. 24. A. Pusch, S. P. Bremner, M. J. Y. Tayebjee, and N. J. E. Daukes, Appl.
     Phys. Lett. 118, 151103 (2021). https://doi.org/10.1063/5.0049120, Google
     ScholarScitation, ISI
 25. 25. H. Esmaielpour, B. K. Durant, K. R. Dorman, V. R. Whiteside, J. Garg,
     T. D. Mishima, M. B. Santos, I. R. Sellers, J. F. Guillemoles, and D.
     Suchet, Appl. Phys. Lett. 118, 213902 (2021).
     https://doi.org/10.1063/5.0052600, Google ScholarScitation
 26. 26. T. N. Singh-Rachford and F. N. Castellano, Coord. Chem. Rev. 254, 2560
     (2010). https://doi.org/10.1016/j.ccr.2010.01.003, Google ScholarCrossref
 27. 27. Z. Huang, X. Li, M. Mahboub, K. M. Hanson, V. M. Nichols, H. Le, M. L.
     Tang, and C. J. Bardeen, Nano Lett. 15, 5552 (2015).
     https://doi.org/10.1021/acs.nanolett.5b02130, Google ScholarCrossref
 28. 28. M. Wu, D. N. Congreve, M. W. B. Wilson, J. Jean, N. Geva, M. Welborn,
     T. Van Voorhis, V. Bulovi, M. G. Bawendi, and M. A. Baldo, Nat. Photonics
     10, 31 (2016). https://doi.org/10.1038/nphoton.2015.226, Google
     ScholarCrossref
 29. 29. S. Han, R. Deng, Q. Gu, L. Ni, U. Huynh, J. Zhang, Z. Yi, B. Zhao, H.
     Tamura, A. Pershin, H. Xu, Z. Huang, S. Ahmad, M. Abdi-Jalebi, A.
     Sadhanala, M. L. Tang, A. Bakulin, D. Beljonne, X. Liu, and A. Rao, Nature
     587, 594 (2020). https://doi.org/10.1038/s41586-020-2932-2, Google
     ScholarCrossref
 30. 30. X. Luo, Y. Han, Z. Chen, Y. Li, G. Liang, X. Liu, T. Ding, C. Nie, M.
     Wang, F. N. Castellano, and K. Wu, Nat. Commun. 11, 28 (2020).
     https://doi.org/10.1038/s41467-019-13951-3, Google ScholarCrossref
 31. 31. L. Nienhaus, J. P. Correa-Baena, S. Wieghold, M. Einzinger, T. A. Lin,
     K. E. Shulenberger, N. D. Klein, M. Wu, V. Bulović, T. Buonassisi, M. A.
     Baldo, and M. G. Bawendi, ACS Energy Lett. 4, 888 (2019).
     https://doi.org/10.1021/acsenergylett.9b00283, Google ScholarCrossref
 32. 32. Z. A. Vanorman, J. Lackner, S. Wieghold, K. Nienhaus, G. U. Nienhaus,
     and L. Nienhaus, Appl. Phys. Lett. 118, 203903 (2021).
     https://doi.org/10.1063/5.0050185, Google ScholarScitation
 33. 33. A. Luque and A. Martí, Phys. Rev. Lett. 78, 5014 (1997).
     https://doi.org/10.1103/PhysRevLett.78.5014, Google ScholarCrossref, ISI
 34. 34. Y. Okada, N. J. Ekins-Daukes, T. Kita, R. Tamaki, M. Yoshida, A. Pusch,
     O. Hess, C. C. Phillips, D. J. Farrell, K. Yoshida, N. Ahsan, Y. Shoji, T.
     Sogabe, and J. F. Guillemoles, Appl. Phys. Rev. 2, 021302 (2015).
     https://doi.org/10.1063/1.4916561, Google ScholarScitation, ISI
 35. 35. D. Huang, L. Ding, Y. Xue, J. Guo, Y. J. Zhao, and C. Persson, Appl.
     Phys. Lett. 118, 043901 (2021). https://doi.org/10.1063/5.0034852, Google
     ScholarScitation, ISI

 1. © 2022 Author(s). Published under an exclusive license by AIP Publishing.