Synergizing Self‐Assembled Monolayer and Atomic Layer to Suppress Electron‐Phonon Coupling in Perovskite Photodetectors

ABSTRACT Inverted perovskite photodetectors frequently suffer from severe non‐radiative recombination and hindered charge extraction originating from energy level mismatches and deep‐level defects at the buried interface. To address these challenges, we propose a synergistic interface engineering strategy that combines an asymmetric carbazole‐based self‐assembled monolayer (4PABCz) with an ultrathin Al 2 O 3 layer deposited via atomic layer deposition (ALD). While the 4PABCz organic layer provides optimal energy level alignment for efficient hole extraction, the precisely controlled 1 nm ALD Al 2 O 3 layer effectively passivates uncoordinated Pb 0 defects without impeding quantum tunneling of charge transport. This non‐destructive dual‐modification architecture significantly improves the room‐temperature crystallization of MAPbI 3 perovskite and physically suppresses electron‐phonon coupling. Consequently, the optimized device exhibits an ultralow dark current (2 × 10 −10 A) and a remarkable specific detectivity of 6.57 × 10 12 Jones (based on the dark current). Furthermore, the devices exhibit improved operational stability, maintaining a robust steady‐state photocurrent under continuous illumination for over 18 h. This work highlights the application potential of combining organic self‐assembled monolayers with inorganic atomic layer deposition in the field of high‐performance perovskite optoelectronic devices.