Gradient bandgap enables >13% efficiency sulfide Kesterite solar cells with open-circuit voltage over 800 mV

Kang Yin; Jinlin Wang; Licheng Lou; Xiao Xu; Bowen Zhang; Menghan Jiao; Jiangjian Shi; Dongmei Li; Huijue Wu; Yanhong Luo; Qingbo Meng

arXiv · 2404.00291

Gradient bandgap enables >13% efficiency sulfide Kesterite solar cells with open-circuit voltage over 800 mV

Kang Yin·Jinlin Wang·Licheng Lou·Xiao Xu·Bowen Zhang·Menghan Jiao·Jiangjian Shi·Dongmei Li·Huijue Wu·Yanhong Luo·Qingbo Meng

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Abstract

Sulfide Kesterite Cu2ZnSnS4 (CZTS), a nontoxic and low-cost photovoltaic material, has always being facing severe charge recombination and poor carrier transport, resulting in the cell efficiency record stagnating around 11% for years. Gradient bandgap is a promising approach to relieve these issues, however, has not been effectively realized in Kesterite solar cells due to the challenges in controlling the gradient distribution of alloying elements at high temperatures. Herein, targeting at the Cd alloyed CZTS, we propose a pre-crystallization strategy to reduce the intense vertical mass transport and Cd rapid diffusion in the film growth process, thereby realizing front Cd-gradient CZTS absorber. The Cd-gradient CZTS absorber, exhibiting downward bending conduction band structure, has significantly enhanced the minority carrier transport and additionally improved band alignment and interface property of CZTS/CdS heterojunction. Ultimately, we have achieved a champion total-area efficiency of 13.5% (active-area efficiency: 14.1%) in the cell and in particular a high open-circuit voltage of >800 mV. We have also achieved a certified total-area cell efficiency of 13.16%, realizing a substantial step forward for the pure sulfide Kesterite solar cell.

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Kang Yin, Jinlin Wang, Licheng Lou, Xiao Xu, Bowen Zhang, Menghan Jiao, Jiangjian Shi, Dongmei Li, Huijue Wu, Yanhong Luo, Qingbo Meng. 2024-03-30. Gradient bandgap enables >13% efficiency sulfide Kesterite solar cells with open-circuit voltage over 800 mV. https://arxiv.org/abs/2404.00291

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