Affiliation:
1. Shenzhen Key Laboratory of Advanced Thin Films and Applications Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic Engineering State Key Laboratory of Radio Frequency Heterogeneous Integration Shenzhen University Shenzhen Guangdong 518060 China
2. Institut des Sciences Chimiques de Rennes UMR 6226 Université de Rennes Rennes F‐35000 France
Abstract
AbstractKesterite Cu2ZnSnS4 (CZTS) solar cells with CdS buffer layers have the problem of toxicity and cliff‐like energy band diagram disfavoring higher photoelectric conversion efficiency (PCE (%)). The preparation method for ZnSnO buffer layers which enable Cd‐free CZTS solar cells to reach the certified PCE (%) of 11.4 is limited to atomic layer deposition and sputtering deposition severely reduces PCE (%). Here, it is showed that sputtering deposited ZnSnN2 is an efficient buffer layer for Cd‐free CZTS solar cell, and without antireflection coating or additional passivation layers its champion PCE (%) has reached 10.00 which is comparable to the certified value. No buried junction and current blocking behavior are observed in the CZTS\ZnSnN2 junctions. Elemental inter‐diffusion is observed at the interface between CZTS and ZnSnN2. Most importantly, the energy band of ZnSnN2 is well‐matched with that of CZTS. The former straddles the latter. The conduction band offset is spike‐like with the conduction band of ZnSnN2 higher than that of CZTS, which effectively suppresses interface recombination and results in PCE (%) comparable to the certified value.
Funder
National Natural Science Foundation of China
Basic and Applied Basic Research Foundation of Guangdong Province