Affiliation: | 1. School of Chemical Engineering and Technology, Tianjin University, 135 Yaguan Road, Tianjin, 300350 China
Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL Valais Wallis), CH-1951 Sion, Switzerland
Tianjin Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072 China;2. Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL Valais Wallis), CH-1951 Sion, Switzerland
Swiss Federal Laboratories for Materials Science and Technology (EMPA), 8600 Dübendorf, Switzerland;3. Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL Valais Wallis), CH-1951 Sion, Switzerland;4. School of Chemical Engineering and Technology, Tianjin University, 135 Yaguan Road, Tianjin, 300350 China;5. Swiss Federal Laboratories for Materials Science and Technology (EMPA), 8600 Dübendorf, Switzerland |
Abstract: | Organic–inorganic metal halide perovskite solar cells (PSCs) have achieved certified power conversion efficiency (PCE) of 25.2% with complex compositional and bandgap engineering. However, the thermal instability of methylammonium (MA) cation can cause the degradation of the perovskite film, remaining a risk for the long-term stability of the devices. Herein, a unique method is demonstrated to fabricate highly phase-stable perovskite film without MA by introducing cesium chloride (CsCl) in the double cation (Cs, formamidinium) perovskite precursor. Moreover, due to the suboptimal bandgap of bromide (Br−), the amount of Br− is regulated, leading to high power conversion efficiency. As a result, MA-free perovskite solar cells achieve remarkable long-term stability and a PCE of 20.50%, which is one of the best results for MA-free PSCs. Moreover, the unencapsulated device retains about 80% of the original efficiencies after a 1000 h aging study. These results provide a feasible approach to enhance solar cell stability and performance simultaneously, paving the way for commercializing PSCs. |