Control of valence band offset at CdS/Cu(In, Ga)Se2 interface by inserting wide-bandgap materials for suppression of interfacial recombination in Cu(In, Ga)Se2 solar cells. (9th July 2015)

• Record Type: Journal Article
• Authors: Nishimura, Takahito; Hirai, Yoshiaki; Kurokawa, Yasuyoshi; Yamada, Akira
• Is Part Of: Japanese journal of applied physics. Volume 54:Number 8(2015:Aug.)Supplement 1
• Publication Date: 2015-07-09
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/JJAP.54.08KC08
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: We inserted Cu(In, Ga)3 Se5 into the CdS/Cu(In, Ga)Se2 interface of Cu(In, Ga)Se2 solar cells with a flat band profile and energy bandgaps ( E g ) of 1.2 and 1.4 eV in order to investigate the repelling of holes by the effect of valence band offset (Δ E v ). We found that open circuit voltage ( V OC ) was clearly improved from 0.66 to 0.75 V with E g of 1.4 eV, although V OC was only increased from 0.63 to 0.64 V with E g of 1.2 eV. For high efficiency, we fabricated Cu(In, Ga)Se2 solar cells with a single-graded band profile and an average E g of 1.4 eV. Eventually, a conversion efficiency of 14.4% was obtained when Cu(In, Ga)3 Se5 with a thickness of 30 nm was inserted, although the conversion efficiency was 10.5% without Cu(In, Ga)3 Se5 . These results suggest the importance of Δ E v in the suppression of interfacial recombination by repelling holes and possibility that the highest efficiency of Cu(In, Ga)Se2 solar cells with an average E g of 1.4 eV could be achieved.