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Cu–Zn disorder and band gap fluctuations in Cu 2 ZnSn(S,Se) 4 : Theoretical and experimental investigations (Phys. Status Solidi B 2/2016)
Author(s) -
Scragg Jonathan J. S.,
Larsen Jes K.,
Kumar Mukesh,
Persson Clas,
Sendler Jan,
Siebentritt Susanne,
Platzer Björkman Charlotte
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201670508
Subject(s) - raman spectroscopy , band gap , semiconductor , solar cell , photoluminescence , condensed matter physics , materials science , electronic band structure , chemistry , chemical physics , optoelectronics , physics , optics
Cu 2 ZnSn(S,Se) 4 is a compound semiconductor that is in development for solar cells based on earth‐abundant materials. Scragg et al. (pp. 247‐254 ) examine one of the troubling issues with this material, which is cation disorder in the crystal structure. The authors attempt to quantify the cation disorder using a physical model, thereby estimating the defect density that it causes. Then, they present calculations of the band structure that indicate much larger band gap fluctuations arising from cation disorder than had previously been considered: this could be a serious problem for the open circuit voltage obtainable from Cu 2 ZnSn(S,Se) 4 ‐based solar cells. Experiments using Raman spectroscopy and photoluminescence combined with in‐situ heat‐treatments confirm that the energy of the dominant band‐to‐band recombination pathway correlates perfectly to the progress of the order‐disorder transition. These results suggest that elimination of cation disorder could be key to future improvements in the efficiency of this type of solar cell.