Molecular N‐Type Doping Enables Schottky Interface Engineering in HTL‐Free Self‐Powered Perovskite Photodetectors: From Visible to Near‐Infrared Detection

Hole‐transport‐layer‐free perovskite photodetectors offer a simplified architecture for self‐powered optoelectronics, but weak interfacial band bending and carrier back‐injection at the transparent electrode/perovskite contact limit their performance. Herein, we introduce direct incorporation of N‐DMBI into methylammonium lead iodide (MAPbI 3 ) absorber layers as a molecular n‐type doping strategy to engineer the indium tin oxide (ITO)/MAPbI 3 Schottky interface. Hydride‐transfer‐enabled electron donation modulates the Fermi‐level alignment without significantly altering the optical bandgap, thereby strengthening the built‐in potential and suppressing dark‐condition electron back‐injection. An optimized N‐DMBI concentration of 2.0 mM balances interfacial band engineering with bulk film quality preservation, yielding an ultralow dark current density of 1.39 × 10 −12 A cm −2 , a responsivity of 0.388 A W −1 at 630 nm under zero bias, a Johnson‐noise‐limited detectivity of 2.24 × 10 13 Jones at 630 nm under zero bias, a linear dynamic range of 127 dB, and microsecond‐scale response times. Building on this, we further extend the molecular doping strategy to narrow‐bandgap tin‐lead perovskite, achieving a dark current density of 1.33 × 10 −10 A cm −2 and a detectivity of 3.81 × 10 12 Jones at 940 nm under zero bias, confirming the generalizability of this approach across perovskite compositions and broadening photodetection into the near‐infrared region.