In‐Situ Cyclized Polyacrylonitrile as an Electron Selective Layer for n‐i‐p Perovskite Solar Cell with Enhanced Efficiency and Stability

In‐situ cyclized polyacrylonitrile (CPAN) is developed to replace n‐type metal oxide semiconductors (TiO2 or SnO2) as an electron selective layer (ESL) for highly efficient and stable n‐i‐p perovskite solar cells (PSCs). The CPAN layer is fabricated via facile in‐situ cyclization reaction of polyacrylonitrile (PAN) coated on a conducting glass substrate. The CPAN layer is robust and insoluble in common solvents, and possesses n‐type semiconductor properties with a high electron mobility of 4.13 x 10‐3 cm2 V‐1 s‐1. With the CPAN as an ESL, the PSC affords a power conversion efficiency (PCE) of 23.12%, which is the highest for the n‐i‐p PSCs with organic ESLs. Moreover, the device with the CPAN layer holds superior operational stability, maintaining over 90% of their initial efficiency after 500 h continuous light soaking. These results confirm that the CPAN layer would be a desirable low‐cost and efficient ESL for n–i–p PSCs and other photoelectronic devices with high performance and stability.