Identification of Killer Defects in Kesterite Thin-Film Solar Cells

Sunghyun Kim, Ji Sang Park, Aron Walsh

Research output: Contribution to journalArticlepeer-review

139 Scopus citations


Nonradiative electron-hole recombination is the bottleneck to efficient kesterite thin-film solar cells. We have performed a search for active point defect recombination centers using first-principles calculations. We show that the anion vacancy in Cu2ZnSnS4 (CZTS) is electrically benign without a donor level in the band gap. VS can still act as an efficient nonradiative site through the aid of an intermediate excited state involving electron capture by Sn. The bipolaron associated with Sn4+ to Sn2+ two-electron reduction stabilizes the neutral sulfur vacancy over the charged states; however, we demonstrate a mechanism whereby nonradiative recombination can occur via multiphonon emission. Our study highlights that defect-mediated recombination does not require a charge transition level deep in the band gap of a semiconductor. We further identify SnZn as the origin of persistent electron trapping/detrapping in kesterite photovoltaic devices, which is suppressed in the selenide compound.

Original languageEnglish
Pages (from-to)496-500
Number of pages5
JournalACS Energy Letters
Issue number2
StatePublished - 9 Feb 2018

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© 2018 American Chemical Society.


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