Homogeneous Na incorporation for industrial‐scale application of Cu(In, Ga)(Se, S)2 solar cells. (2nd November 2017)

• Record Type: Journal Article
• Authors: Park, Ji Hun; Lee, Seunghwan; Song, EunHo; Shin, SangHo; Kang, ChangHo; Yoon, HyungSeok; Lee, Seunghun; Yang, JungYup; Lee, Dongho; Kim, Dongseop; Nam, Junggyu
• Is Part Of: Progress in photovoltaics. Volume 26:Number 2(2018)
• Page Start: 112
• Page End: 126
• Publication Date: 2017-11-02
• Subjects: Cu(In, Ga)(Se, S)2 solar cells -- large size module -- Na doping effect -- scaling up; Solar cells -- Periodicals; Photovoltaic cells -- Periodicals; Solar power plants -- Periodicals; 621.31245
• DOI: 10.1002/pip.2951
• Languages: English
• ISSNs: 1062-7995

Abstract

Abstract: We achieve large‐area (1602 × 902 mm 2 ) doping uniformity without layer peel‐offs, based on a dual Na source, ie, partial Na out‐diffusion from soda‐lime glass and a homogeneously sputtered CuGa:NaF layer as an auxiliary source. We systematically investigate the optoelectronic, microstructural, and compositional characteristics of Cu(In, Ga)(Se, S)2 solar cells and analyze the underlying mechanism in detail. Na out‐diffusion from soda‐lime glass initially improves the cell performance according to the defect passivation and Na doping effects; further Na incorporation using the Na‐doped layer enhances J SC, FF, and film conductivity, which is likely due to the enhanced cell homogeneity and the alleviation of carrier transport‐limited characteristics. Excessive Na incorporation triggers the possible generation of layer peel‐offs, which is closely related to the reduced adhesion force, void generation, decrease in S/(S + Se) ratio, Ga redistribution, bandgap reduction, and increase in the low‐energy photoluminescence. These results indicate that the voids are created via Kirkendal mechanism based on the variability in atomic diffusion rates following compositional changes, resulting from the insufficiency in Na consumption or sulfurization. It is noted that an in‐line codeposition technique enables realization of high‐level Na doping as well as void‐free interface state by suppressing the defect generation, which yields high‐efficiency commercial‐scale Cu(In, Ga)(Se, S)2 modules without layer peel‐off problems. Abstract : This article is the investigation of large‐area (1602 × 902 mm 2 ) doping uniformity without layer peel‐offs, based on a dual sodium source, ie, partial Na out‐diffusion from soda‐lime glass and a homogeneously sputtered CuGa:NaF layer as an auxiliary source for the application of Cu(In, Ga)(Se, S)2 (CIGSS) solar module. In addition, we systematically investigate the optoelectronic, microstructural, and compositional characteristics of CIGSS solar cells and analyze the underlying mechanism in detail.