Progress of inverted inorganic cesium lead halide solar cells

Inorganic cesium lead halide perovskite solar cells (PSCs) have attracted tremendous interest due to the outstanding thermal and light stability compared with their organic-inorganic hybrid counterparts. In contrast with the regular (n-i-p) structure, inverted (p-i-n) inorganic PSCs are gaining more attention owing to their dopantfree and low-temperature fabrication of charge transport layer, as well as superior compatibility in tandem cells. With the enormous efforts in inverted inorganic PSCs, prominent progress has been achieved in enhancing the device efficiency and stability. In this review, the progress of inverted inorganic PSCs is comprehensively summarized from the aspects of inorganic perovskite films, interfaces, charge transport materials, and buffer layers. Furthermore, perspectives on the possible development directions of inverted inorganic PSCs are given to provide guidelines for further optimizing the device performance and promoting their applications in photovoltaic field.