Identification of Killer Defects in Kesterite Thin-Film Solar Cells

Sunghyun Kim; Ji Sang Park; Aron Walsh

doi:10.1021/acsenergylett.7b01313

Identification of Killer Defects in Kesterite Thin-Film Solar Cells

Sunghyun Kim, Ji Sang Park, Aron Walsh

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

39 Citations (Scopus)

Abstract

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. V_S 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 Sn_Zn as the origin of persistent electron trapping/detrapping in kesterite photovoltaic devices, which is suppressed in the selenide compound.

Original language	English
Pages (from-to)	496-500
Number of pages	5
Journal	ACS Energy Letters
Volume	3
Issue number	2
DOIs	https://doi.org/10.1021/acsenergylett.7b01313
Publication status	Published - 2018 Feb 9

Bibliographical note

Funding Information:
We acknowledge support from the Royal Society, the EPSRC (Grant No. EP/K016288/1), and the EU Horizon2020 Framework (STARCELL, Grant No. 720907). We are grateful to the UK Materials and Molecular Modeling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1). Via our membership of the UK’s HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). We also thank Audrius Alkauskas for sharing his code for the nonradiative recombination rate calculations.

All Science Journal Classification (ASJC) codes

Chemistry (miscellaneous)
Renewable Energy, Sustainability and the Environment
Fuel Technology
Energy Engineering and Power Technology
Materials Chemistry

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title = "Identification of Killer Defects in Kesterite Thin-Film Solar Cells",

abstract = "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.",

author = "Sunghyun Kim and Park, {Ji Sang} and Aron Walsh",

note = "Funding Information: We acknowledge support from the Royal Society, the EPSRC (Grant No. EP/K016288/1), and the EU Horizon2020 Framework (STARCELL, Grant No. 720907). We are grateful to the UK Materials and Molecular Modeling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1). Via our membership of the UK{\textquoteright}s HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). We also thank Audrius Alkauskas for sharing his code for the nonradiative recombination rate calculations.",

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