Bandgap engineering of Cu2CdxZn1−xSnS4 alloy for photovoltaic applications: A complementary experimental and first-principles study
Bandgap engineering of Cu2CdxZn1−xSnS4 alloy for photovoltaic applications: A complementary experimental and first-principles study
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DOI：
10.1063/1.4829457
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发表时间：
2013-11
影响因子：
3.2
通讯作者：
Zhenyu Xiao;Yongfeng Li;B. Yao;R. Deng;Z. Ding;Tom Wu;Gang Yang;C. Li;Zi-Yuan Dong;
中科院分区：
文献类型：
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作者：
Zhenyu Xiao;Yongfeng Li;B. Yao;R. Deng;Z. Ding;Tom Wu;Gang Yang;C. Li;Zi-Yuan Dong;
报道了一种新型光伏材料Cu2CdxZn1−xSnS4(CCZTS)的带隙工程。采用溶胶凝胶法制备了不同Cd含量、单一晶相的CCZTS合金薄膜。光吸收测量表明，随着Cd含量从x=0到1的变化，开斯特型CCZTS薄膜的禁带宽度可以在1.55-1.09 eV范围内连续可调。霍尔效应测量表明，随着Cd含量的增加，CCZTS薄膜的空穴浓度降低。X=0.47的CCZTS基太阳能电池的功率转换效率为1.2%。基于混合泛函方法的第一性原理计算表明，随着Cd含量的增加，开斯特CCZTS合金的禁带宽度单调减小，支持实验结果。此外，Cu2ZnSnS4/Cu2CdSnS4界面具有价带偏移较小的I型能带排列，解释了CCZTS禁带宽度随Cd含量增加而变窄的原因。我们的结果表明，CCZTS合金是一种潜在的适合于制备具有不同带隙定制吸收层的高效多结串联太阳电池的材料。
We report on bandgap engineering of an emerging photovoltaic material of Cu 2Cdx Zn 1−x SnS 4 (CCZTS) alloy. CCZTS alloy thin films with different Cd contents and single kesterite phase were fabricated using the sol-gel method. The optical absorption measurements indicate that the bandgap of the kesterite CCZTS alloy can be continuously tuned in a range of 1.55–1.09 eV as Cd content varied from x = 0 to 1. Hall effect measurements suggest that the hole concentration of CCZTS films decreases with increasing Cd content. The CCZTS-based solar cell with x = 0.47 demonstrates a power conversion efficiency of 1.2%. Our first-principles calculations based on the hybrid functional method demonstrate that the bandgap of the kesterite CCZTS alloy decreases monotonically with increasing Cd content, supporting the experimental results. Furthermore, Cu 2ZnSnS4/Cu2CdSnS4 interface has a type-I band-alignment with a small valence-band offset, explaining the narrowing of the bandgap of CCZTS as the Cd content increases. Our results suggest that CCZTS alloy is a potentially suitable material to fabricate high-efficiency multi-junction tandem solar cells with different bandgap-tailored absorption layers.