TY - JOUR
T1 - Elucidating Structural Disorder and the Effects of Cu Vacancies on the Electronic Properties of Cu2ZnSnS4
AU - Yu, Kuang
AU - Carter, Emily A.
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/2/9
Y1 - 2016/2/9
N2 - Although a promising photovoltaic material that is inexpensive and easy to manufacture, Cu2ZnSnS4 (CZTS) suffers from a low open circuit voltage thought to be due to local potential fluctuations caused by a disordered Cu/Zn sublattice. The disordered character of CZTS is difficult to study experimentally and has been universally neglected in computational studies. Here, we develop a cluster expansion model that enables simulation of the order-disorder phase transition in CZTS for the first time. With a proper atomic structure of the disordered phase in hand, we investigate the temperature-dependent voltage loss in CZTS, illustrating intrinsic limitations of existing synthesis methods and suggesting an optimal annealing temperature. We offer one explanation why Cu-poor CZTS is optimally efficient, as Cu vacancies increase the band gap via interactions between free carriers and the disordered nature of as-grown CZTS. Accordingly, increasing carrier concentrations may be an effective strategy to flatten the fluctuating potentials.
AB - Although a promising photovoltaic material that is inexpensive and easy to manufacture, Cu2ZnSnS4 (CZTS) suffers from a low open circuit voltage thought to be due to local potential fluctuations caused by a disordered Cu/Zn sublattice. The disordered character of CZTS is difficult to study experimentally and has been universally neglected in computational studies. Here, we develop a cluster expansion model that enables simulation of the order-disorder phase transition in CZTS for the first time. With a proper atomic structure of the disordered phase in hand, we investigate the temperature-dependent voltage loss in CZTS, illustrating intrinsic limitations of existing synthesis methods and suggesting an optimal annealing temperature. We offer one explanation why Cu-poor CZTS is optimally efficient, as Cu vacancies increase the band gap via interactions between free carriers and the disordered nature of as-grown CZTS. Accordingly, increasing carrier concentrations may be an effective strategy to flatten the fluctuating potentials.
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U2 - 10.1021/acs.chemmater.5b04351
DO - 10.1021/acs.chemmater.5b04351
M3 - Article
AN - SCOPUS:84957960989
SN - 0897-4756
VL - 28
SP - 864
EP - 869
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 3
ER -