Intermeshing Electron Transporting Layer for Efficient and Stable CsPbI2Br Perovskite Solar Cells with Open Circuit Voltage over 1.3 V

Inorganic CsPbI2Br perovskite has gained great attention due to its outstanding overall stabilities and great potential for application in semitransparent and tandem solar cells. However, the power conversion efficiencies (PCEs) of CsPbI2Br-based perovskite solar cells (pero-SCs) are being limited by their severe energy loss (Eloss) due to the unfavorable device interface and defects. Here, an intermeshing SnO2 (Im-SnO2) electron transporting layer (ETL) is subtly constructed by combining two types of SnO2 with complementary electronic/physical properties for suppressing the notorious Eloss. With this strategy, the defects of conventional SnO2 ETL can be greatly improved, which could facilitate charge extracting, increase the crystallinity and orientation of CsPbI2Br film, construct a cascade energy level in the device, simultaneously. Consequently, the Eloss of CsPbI2Br pero-SC can be remarkably reduced to below 0.6 eV, delivering an excellent PCE of 16.10% with a Voc as high as 1.31 V. To the best of our knowledge, this result is one of the few CsPbI2Br pero-SCs that enable high Voc without sacrificing efficiency. In addition, the devices show high stability under both strong UV irradiation for 300 h and an ambient atmosphere for 1000 h.