201. Over 15% efficient wide-band-gap Cu(In,Ga)S2solar cell: Suppressing bulk and interface recombination through composition engineering
- Author
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Shukla, Sudhanshu, Sood, Mohit, Adeleye, Damilola, Peedle, Sean, Kusch, Gunnar, Dahliah, Diana, Melchiorre, Michele, Rignanese, Gian-Marco, Hautier, Geoffroy, Oliver, Rachel, and Siebentritt, Susanne
- Abstract
The progress of Cu(In,Ga)S2remains 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 initiomodeling, 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/CuGaas 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 Vocof 902 mV from a H2S-free, Cd-free, and KCN-free process.
- Published
- 2021
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