Over 15% efficient wide-band-gap Cu(In,Ga)S2 solar cell: Suppressing bulk and interface recombination through composition engineering
(2021) JOULE — (2021)
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- Authors
Shukla, Sudhanshu 
Adeleye, Damilola
- Abstract
- The progress of Cu(In,Ga)S2 remains significantly limited mainly due to photovoltage (Voc) losses in the bulk and at the interfaces. Here, via a combination of photoluminescence, cathodoluminescence, electrical measurements, and ab initio modeling, we address the bulk and interface losses to improve ∼1.6-eV-band-gap (Eg) Cu(In,Ga)S2. The optoelectronic quality of the absorber improves upon reducing the [Cu]/[Ga+In] (CGI) ratio, as manifested by the suppression of deep defects, higher quasi-Fermi level splitting (QFLS), improved charge-carrier lifetime, and higher Voc. We identify antisite CuIn/CuGa as a major performance-limiting deep defect by comparing the formation energies of various intrinsic defects. Interface recombination is suppressed using a Zn(O,S) buffer layer in Cu-poor devices, which leads to the activation energy of recombination equal to the Eg. We demonstrate an efficiency of 15.2% with Voc of 902 mV from a H2S-free, Cd-free, and KCN-free process.
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Citations
Shukla, S., Sood, M., Adeleye, D., Peedle, S., Kusch, G., Dahliah, D., Melchiorre, M., Rignanese, G.-M., Hautier, G., Oliver, R., & Siebentritt, S. (2021). Over 15% efficient wide-band-gap Cu(In,Ga)S2 solar cell: Suppressing bulk and interface recombination through composition engineering. JOULE. Published. https://doi.org/10.1016/j.joule.2021.05.004 (Original work published 2021)