Breaking Interfacial Charge Transport Limitations Enabled by Heterojunction Dielectric Equilibrium in Perovskite Solar Cells.

Heterointerface properties of perovskite solar cells (PVSCs) are critical in determining efficient carrier transport. Conventional interface engineering is insufficient to completely address the dilemma of low charge transport efficiency at the heterointerface with side effects, especially at the perovskite buried interface with complex chemical environments. Here, we have improved effective dielectric matching and constructed an efficient charge transport channel at the heterointerface of perovskite/charge transport layer by narrowing the difference in dielectric constants. The charge transfer resistance and electron trapping radius at the perovskite heterointerface are effectively reduced by the heterojunction dielectric equilibrium strategy for the first time, thus accelerating the interfacial charge transfer. Meanwhile, we further elucidate the effect of dielectric equilibrium on the charge carrier transport across the heterointerface. The resulting device acquires a record efficiency of 26.77% (certified as 26.01%) for n-i-p PVSCs prepared by a unique heterojunction dielectric equilibrium strategy and excellent operational stability.