On the origin of band-tails in kesterite

By G. Rey, G. Larramona, S. Bourdais, C. Choné, B. Delatouche, A. Jacob, Gilles Dennler, S. Siebentritt. Solar Energy Materials and Solar Cells, 2017

164 citations recorded by the source corpus.

Abstract Kesterite Cu 2 ZnSn( S x Se 1 − x ) 4 is an attractive earth-abundant material for low-cost thin film photovoltaics with the capability to achieve power production in the terawatt range and therefore to supply a significant part of the global electricity needs. Despite its advantageous optical and electrical properties for photovoltaic applications, the large band tailing causes voltage losses that limit the efficiency of kesterite-based devices. Here we show that the band-tailing originates mainly from band-gap fluctuations attributable to chemical composition variations at nanoscale; while electrostatic fluctuations play a lesser role. Absorption measurement reveal that the Cu-Zn disorder, always present in kesterite Cu 2 ZnSn( S x Se 1 − x ) 4 , is not the main source of the large band tailing. Instead defect clusters having a significant impact on the band-edge energies, e.g. [2 Cu Zn − + Sn Zn 2 + ], are proposed as the main origin for the kesterite band tail.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/c76d44b7919cb34eb9f1fbc6bd154e354775384e