Four-terminal tandem solar cells using CH₃NH₃PbBr₃ by spectrum splitting

In this work, the use of a high bandgap perovskite solar cell in a spectrum splitting system is demonstrated. A remarkable energy conversion efficiency of 23.4% is achieved when a CH₃NH₃PbBr₃ solar cell is coupled with a 22.7% efficient silicon passivated emitter rear locally diffused solar cell. Relative enhancements of >10% are demonstrated by CH₃NH₃PbBr₃/CH₃NH₃PbI₃ and CH₃NH₃PbBr₃/multicrystalline-screen-printed-Si spectral splitting systems with tandem efficiencies of 13.4% and 18.8%, respectively. The former is the first demonstration of an all perovskite split spectrum system. The CH₃NH₃PbBr₃ cell on a mesoporous structure was fabricated by the vapor-assisted method while the planar CH₃NH₃PbI₃ cell was fabricated by the gas-assisted method. This work demonstrates the advantage of the higher voltage output from the high bandgap CH₃NH₃PbBr₃ cell and its suitability in a tandem system.