Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 18: Optical Analysis of Thin Films (Reflection, Ellipsometry, Raman, IR-DUV Spectroscopy, ...): Session I

DS 18.8: Talk

Wednesday, March 14, 2018, 12:00–12:15, H 0111

Electron capture by Sn polaron in Kesterite solar cells — •Sunghyun Kim¹, Ji-Sang Park¹, and Aron Walsh^{1, 2} — ¹Thomas Young Centre and Department of Materials, Imperial College London, London, United Kingdom — ²Department of Materials Science and Engineering, Younsei University, Seoul, Republic of Korea

The kesterite mineral, such as Cu2ZnSnS4 (CZTS), has attracted much attention as a replacement of the commercial Cu(In,Ga)S2 light absorber, consisting of only earth-abundant elements, and thus has the potential to support a Terawatt photovoltaic industry. Non-radiative carrier recombination is the likely origin of large open-circuit voltage deficit which is the primary bottleneck for achieving efficient kesterite solar cells. We have performed first-principles calculations within the framework of density functional theory to search for killer recombination centers in CZTS. The sulfur vacancy in CZTS is electrically benign not producing any donor levels in the band gap. However, we find that the sulfur vacancy can act as an efficient non-radiative site with the aid of an intermediate state involving Sn polaron formation. We point out that trap-assisted recombination does not necessarily accompany a charge transition level deep in the band gap of a semiconductor.