Suppressing Non‐Radiative Recombination at Perovskite/C ₆₀ Interface With Electron‐Deficient π–π Stacking Triazine Polymers for Efficient Inverted Perovskite Solar Cells

ABSTRACT Inverted perovskite solar cell has attracted worldwide research attention, but its performances are greatly affected by the non‐radiative recombination loss at interface of perovskite/electron transport layer. Here, we design electron‐deficient π‐expanded 2D covalent triazine polymers to modify the perovskite/C 60 interface, achieving the inhibition of non‐radiative recombination at this interface via regulating the electron extraction rate and reducing I − migration‐induced charged defect's accumulation. The experimental and theoretical calculation results reveal that the electron‐deficient structure and π–π stacking properties in the 2D covalent triazine‐based polymer facilitate electron extraction and transfer from the perovskite to C 60 along the π–π stacking direction. Moreover, the I − migration and the accumulation of charged defects at the interface are effectively suppressed by the anion–π interaction between I − and the electron‐deficient triazine ring. Owing to the positive role of 2D covalent triazine polymers, the corresponding device achieves a power conversion efficiency of 25.54% and maintains >91% of its initial efficiency after tracking at the maximum power point for 1000 h. This work develops an effective interface layer materials for reducing non‐radiative recombination at perovskite/C 60 interface and enhancing device performances.