Integrated 4-Terminal All-Inorganic Perovskite Tandem Solar Cell with Open-Circuit Voltage Exceeding 2.1 V for Water Splitting
Qiang Sun, Zhiguo Zhang, Tao Zhang, Feng Yao, Anjie Gu, Haixuan Yu, Miaomiao Zhang, Xiaoli Zhang, Jun Zhu, Yan Shen, Mingkui Wang
Abstract
This work reports on Sn-Pb binary metal inorganic perovskites as narrow-bandgap absorbers for integrated 4-terminal all-inorganic perovskite tandem solar cells (TSCs). A series of Sn-Pb binary metal CsPb1–xSnxI3-yBry inorganic perovskites with tunable bandgaps ranging from 1.28 to 1.45 eV were synthesized through tuning the Sn-Pb and I-Br contents. The TSC device using a narrow-bandgap CsPb0.5Sn0.5I2.7Br0.3 bottom cell with a wide-bandgap semi-transparent CsPbI1.5Br1.5 top cell achieved a remarkable power conversion efficiency over 18% and a high open-circuit voltage (VOC) of 2.13 V, a very attractive feature for solar fuel production. To the best of our knowledge, this is the first trial of TSCs entirely made of all-inorganic perovskite absorbers, and also the record VOC achieved among double-junction TSCs based on integration of narrow- and wide-bandgap perovskite absorbers so far. Using this novel all-inorganic perovskite TSC in conjunction with a water-splitting system employing Pt/C for hydrogen evolution reaction and Fe/Ni foam for oxygen evolution reaction in alkaline electrolyte, we achieved an unprecedented solar-to-hydrogen efficiency over 13% under standard illumination test conditions.