Heterogeneity of grain boundary properties in Cu2ZnSnS4: A first-principles study

Using first-principles density functional calculations, we investigate the structure and properties of previously unstudied grain boundaries (GBs) in the solar absorber material copper-zinc-tin-sulfide (CZTS). We identify four stable low-Σ value symmetric tilt GBs with low formation energies: Σ3 (11...

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Bibliographic Details
Published in:Journal of applied physics 2023-04, Vol.133 (14)
Main Authors: Hao, Ning-Jing, Ding, Rui-Xue, Tong, Chuan-Jia, McKenna, Keith P.
Format: Article
Language:English
Subjects:
Applied physics
Bonding strength
Chemical bonds
Copper
Crystal defects
Electron states
First principles
Free energy
Grain boundaries
Heat of formation
Heterogeneity
Point defects
Solar energy absorbers
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Summary:Using first-principles density functional calculations, we investigate the structure and properties of previously unstudied grain boundaries (GBs) in the solar absorber material copper-zinc-tin-sulfide (CZTS). We identify four stable low-Σ value symmetric tilt GBs with low formation energies: Σ3 (111) and Σ5 (201), each with two different GB terminations. Compared to CdTe and CuInSe, GBs in the quaternary semiconductor CZTS exhibit a wider variety of electronic states due to the more complex chemical environment near the GB, including under-coordinated atoms and dangling bonds. Further analysis confirms that strong dangling bonds introduce deep gap states in all GBs studied. We also investigate segregation and electronic properties of intrinsic point defects to GBs and find that one of the Σ3 (111) GBs exhibits an abnormal defect segregation behavior that favors Cu-poor (Zn-rich) GB composition, which is beneficial for its overall performance.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0147435