Editing Selenium (section)

===Solar cells===
Selenium was used as the photoabsorbing layer in the first solid-state solar cell, which was demonstrated by the English physicist [[William Grylls Adams]] and his student Richard Evans Day in 1876.<ref>{{cite journal |last1=Adams |first1=William Grylls |last2=Day |first2=Richard Evans |title=The Action of Light on Selenium |journal=Philosophical Transactions of the Royal Society of London |date=1877 |volume=167 |pages=313–349|bibcode=1877RSPT..167..313A }}</ref> Only a few years later, [[Charles Fritts]] fabricated the first thin-film solar cell, also using selenium as the photoabsorber. However, with the emergence of silicon solar cells in the 1950s, research on selenium thin-film solar cells declined. As a result, the record efficiency of 5.0% demonstrated by Tokio Nakada and Akio Kunioka in 1985 remained unchanged for more than 30 years.<ref>{{cite journal |last1=Nakada |first1=Tokio |last2=Kunioka |first2=Akio |title=Polycrystalline Thin-Film TiO 2 /Se Solar Cells |journal=Japanese Journal of Applied Physics |date=1 July 1985 |volume=24 |issue=7A |pages=L536 |doi=10.1143/JJAP.24.L536|bibcode=1985JaJAP..24L.536N |s2cid=118838432 }}</ref> In 2017, researchers from [[IBM]] achieved a new record efficiency of 6.5% by redesigning the device structure.<ref>{{cite journal |last1=Todorov |first1=Teodor K. |last2=Singh |first2=Saurabh |last3=Bishop |first3=Douglas M. |last4=Gunawan |first4=Oki |last5=Lee |first5=Yun Seog |last6=Gershon |first6=Talia S. |last7=Brew |first7=Kevin W. |last8=Antunez |first8=Priscilla D. |last9=Haight |first9=Richard |title=Ultrathin high band gap solar cells with improved efficiencies from the world's oldest photovoltaic material |journal=Nature Communications |date=25 September 2017 |volume=8 |issue=1 |page=682 |doi=10.1038/s41467-017-00582-9|pmid=28947765 |pmc=5613033 |bibcode=2017NatCo...8..682T }}</ref> Following this achievement, selenium has gained renewed interest as a wide bandgap photoabsorber with the potential of being integrated in [[Multi-junction solar cell|tandem]] with lower bandgap photoabsorbers.<ref>{{cite journal |last1=Youngman |first1=Tomas H. |last2=Nielsen |first2=Rasmus |last3=Crovetto |first3=Andrea |last4=Seger |first4=Brian |last5=Hansen |first5=Ole |last6=Chorkendorff |first6=Ib |last7=Vesborg |first7=Peter C. K. |title=Semitransparent Selenium Solar Cells as a Top Cell for Tandem Photovoltaics |journal=Solar RRL |date=July 2021 |volume=5 |issue=7 |doi=10.1002/solr.202100111|s2cid=235575161 }}</ref> In 2024, the first selenium-based tandem solar cell was demonstrated, showcasing a selenium top cell monolithically integrated with a silicon bottom cell.<ref>{{cite journal |last1=Nielsen |first1=Rasmus |last2=Crovetto |first2=Andrea |last3=Assar |first3=Alireza |last4=Hansen |first4=Ole |last5=Chorkendorff |first5=Ib |last6=Vesborg |first6=Peter C.K. |title=Monolithic Selenium/Silicon Tandem Solar Cells |journal=PRX Energy |date=12 March 2024 |volume=3 |issue=1 |page=013013 |doi=10.1103/PRXEnergy.3.013013|arxiv=2307.05996 |bibcode=2024PRXE....3a3013N }}</ref> However, a significant deficit in the [[open-circuit voltage]] is currently the main limiting factor to further improve the efficiency, necessitating defect-engineering strategies for selenium thin-films to enhance the [[carrier lifetime]].<ref>{{cite journal |last1=Nielsen |first1=Rasmus |last2=Youngman |first2=Tomas H. |last3=Moustafa |first3=Hadeel |last4=Levcenco |first4=Sergiu |last5=Hempel |first5=Hannes |last6=Crovetto |first6=Andrea |last7=Olsen |first7=Thomas |last8=Hansen |first8=Ole |last9=Chorkendorff |first9=Ib |last10=Unold |first10=Thomas |last11=Vesborg |first11=Peter C. K. |title=Origin of photovoltaic losses in selenium solar cells with open-circuit voltages approaching 1 V |journal=Journal of Materials Chemistry A |date=2022 |volume=10 |issue=45 |pages=24199–24207 |doi=10.1039/D2TA07729A|s2cid=253315416 }}</ref><ref>{{Cite journal |last1=Nielsen |first1=Rasmus S. |last2=Gunawan |first2=Oki |last3=Todorov |first3=Teodor |last4=Møller |first4=Clara B. |last5=Hansen |first5=Ole |last6=Vesborg |first6=Peter C. K. |date=3 April 2025 |title=Variable-temperature and carrier-resolved photo-Hall measurements of high-performance selenium thin-film solar cells |journal=Physical Review B |volume=111 |issue=16 |pages=165202 |doi=10.1103/PhysRevB.111.165202 |arxiv=2409.12804 |bibcode=2025PhRvB.111p5202N |issn=2469-9950}}</ref> As of now, the only defect-engineering strategy that has been investigated for selenium thin-film solar cells involves [[Laser-heated pedestal growth|crystallizing selenium using a laser]].<ref>{{cite journal |last1=Nielsen |first1=Rasmus |last2=Hemmingsen |first2=Tobias H. |last3=Bonczyk |first3=Tobias G. |last4=Hansen |first4=Ole |last5=Chorkendorff |first5=Ib |last6=Vesborg |first6=Peter C. K. |title=Laser-Annealing and Solid-Phase Epitaxy of Selenium Thin-Film Solar Cells |journal=ACS Applied Energy Materials |date=11 September 2023 |volume=6 |issue=17 |pages=8849–8856 |doi=10.1021/acsaem.3c01464|arxiv=2306.11311 |s2cid=259203956 }}</ref>