An intermeshing electron transporting layer for efficient and stable CsPbI2Br perovskite solar cells with open circuit voltage over 1.3 V

Abstract

Inorganic CsPbI₂Br perovskite has gained great attention due to its outstanding overall stability 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 (E_loss) due to the unfavorable device interface and defects. Here, an intermeshing SnO₂ (Im-SnO₂) electron transporting layer (ELF) is subtly constructed by combining two types of SnO₂ with complementary electronic/physical properties for suppressing the notorious E_loss. With this strategy, the defects of the conventional SnO₂ ETL can be greatly improved, which could simultaneously facilitate charge extraction, increase the crystallinity and orientation of CsPbI₂Br films, and form a cascade energy level in the device. Consequently, the E_loss of CsPbI₂Br pero-SCs can be remarkably reduced to below 0.6 eV, delivering an excellent PCE of 16.10% with a V_oc as high as 1.31 V. To the best of our knowledge, these results are among the best reported for a few CsPbI₂Br pero-SCs that enable high V_oc 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.