Cations Functionalized Carbon Nano‐Dots Enabling Interfacial Passivation and Crystallization Control for Inverted Perovskite Solar Cells

Realizing the full potential of perovskite photovoltaic requires stringent control over nonradiative losses in the devices. Herein, the interfacial carrier recombination of inverted planar perovskite solar cells (PSCs) is suppressed using rationally designed natriumion‐functionalized carbon nano‐dots (CNDs@Na). The binding effect of carbon dots on Na+ inhibits the interstitial occupancy of alkali cations and reduces the microstrain of the polycrystalline film. Furthermore, modified surface wettability improves the ordering and crystal size of perovskite, which restrains ion diffusion and improves interfacial contact, leading to reduced interfacial charge recombination. Consequently, the effective interfacial passivation and crystallization control enhance the photovoltaic performance and long‐term stability of PSCs, resulting in an efficiency of over 20% with negligible hysteresis.