Journal Article

Enhanced photovoltage for inverted planar heterojunction perovskite solar cells

Wang, Zhiping, Tu, Yongguang, Zhao, Lichen, Zhang, Wei, Trindade, Gustavo F., Luo, Deying, Wu, Pan, Zhang, Yifei, Yang, Xiaoyu, Sadhanala, Aditya, Gong, Qihuang, Watts, John F., Chen, Ke, Xu, Zhaojian, Shivanna, Ravichandran, Wu, Jiang, Yang, Wenqiang, Hu, Qin, Liu, Tanghao, Friend, Richard H., Su, Rui, Ye, Fengjun, Snaith, Henry J., Zhu, Rui

2018

Overview

Inverted planar perovskite solar cells offer opportunities for a simplified device structure compared with conventional mesoporous titanium oxide interlayers. However, their lower open-circuit voltages result in lower power conversion efficiencies. Using mixed-cation lead mixed-halide perovskite and a solution-processed secondary growth method, Luo et al. created a surface region in the perovskite film that inhibited nonradiative charge-carrier recombination. This kind of solar cell had comparable performance to that of conventional cells. Science , this issue p. 1442 High open-circuit voltages were achieved for planar perovskite solar cells by creating a graded junction. The highest power conversion efficiencies (PCEs) reported for perovskite solar cells (PSCs) with inverted planar structures are still inferior to those of PSCs with regular structures, mainly because of lower open-circuit voltages ( V oc ). Here we report a strategy to reduce nonradiative recombination for the inverted devices, based on a simple solution-processed secondary growth technique. This approach produces a wider bandgap top layer and a more n-type perovskite film, which mitigates nonradiative recombination, leading to an increase in V oc by up to 100 millivolts. We achieved a high V oc of 1.21 volts without sacrificing photocurrent, corresponding to a voltage deficit of 0.41 volts at a bandgap of 1.62 electron volts. This improvement led to a stabilized power output approaching 21% at the maximum power point.

• Publisher: The American Association for the Advancement of Science
• Subject: Cadmium telluride / Carrier recombination / Current carriers / Energy conversion efficiency / Heterojunctions / Interlayers / Perovskites / Photoelectric effect / Photoelectric emission / Photovoltaic cells / Planar structures / Recombination / Solar cells / Titanium oxide / Titanium oxides