Role of electron-phonon coupling and thermal expansion on band gaps, carrier mobility, and interfacial offsets in kesterite thin-film solar cells.
File(s)
Published version
Author(s)
Monserrat, Bartomeu
Park, Jisang
Kim, Sunghyun
Walsh, A
Type
Journal Article
Abstract
The efficiencies of solar cells based on kesterite Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) are limited by a low open-circuit voltage due to high rates of non-radiative electron-hole recombination. To probe the origin of this bottleneck, we calculate the band offset of CZTS(Se) with CdS, confirming a weak spike of 0.1 eV for CZTS/wurtzite-CdS and a strong spike of 0.4 eV for CZTSe/wurtzite-CdS. We also consider the effects of temperature on the band alignment, finding that increasing temperature significantly enhances the spike-type offset. We further resolve an outstanding discrepancy between the measured and calculated phonon frequencies for the kesterites, and use these to estimate the upper limit of electron and hole mobilities based on optic phonon Fröhlich scattering, which uncovers an intrinsic asymmetry with faster (minority carrier) electron mobility.
Date Issued
2018-05-01
Date Acceptance
2018-04-30
Citation
Applied Physics Letters, 2018, 112 (19)
ISSN
0003-6951
Publisher
AIP Publishing
Journal / Book Title
Applied Physics Letters
Volume
112
Issue
19
Copyright Statement
©2018 The Authors
Sponsor
The Royal Society
Commission of the European Communities
The Royal Society
Grant Number
UF150657
720907
NF170826
Subjects
cond-mat.mtrl-sci
09 Engineering
02 Physical Sciences
Applied Physics
Publication Status
Published online
Article Number
193903
Date Publish Online
2018-05-10