Device Physics of the Carrier Transporting Layer in Planar Perovskite Solar Cells

Abstract Perovskite solar cells (PVSCs) have emerged as a promising candidate for addressing the energy crisis due to their rapid efficiency improvement up to 24.2% within 10 years. The defects existing in perovskite film have been found to be as low as 10 15 cm −3 indicating that the bulk nonradiative recombination loss is very small. The major efficiency loss has been attributed to inefficient carrier transportation and collection, particularly at the interfaces of the carrier transport layers (CTLs). Moreover, the mobile ions that can penetrate into or be blocked by the CTLs have been considered to play a significant role in the determination of device efficiency and stability. The further improvement of the PVSC performances relies on interfacial engineering. Meanwhile, it is highly desirable to gain an in‐depth physical understanding of interfacial engineering in PVSCs. Herein, the recent works on CTLs in planar PVSCs are reviewed and the device physics for designing high‐performance PVSCs is unveiled. This work describes the (1) materials and strategies for efficient CTLs; (2) effects of mobile ions and the influence of CTLs; and (3) theoretical modeling and understanding of PVSCs. This work can, therefore, contribute to designing and improving high‐performance PVSCs for future practical commercialized applications.