Ultrathin Quasi‐2D Perovskite‐Organic Segregated‐Structure Coupling for High‐Performance Narrowband Photomultiplication Detectors

ABSTRACT High spectral selectivity and low power operation remain a core goal for miniaturized optoelectronic sensors and imaging systems. In this work, a coupled separation structure based on quasi‐2D perovskite (BA 2 MA 4 Pb 5 I 16 ) and a trap‐type organic bulk‐heterojunction (P3HT: PC 71 BM = 100:1, wt/wt) is employed to realize a highly spectrally selective photomultiplication‐type narrowband photodetector (PM‐NPD) with low‐power operation. The intrinsically ordered crystalline structure of the quasi‐2D perovskite layer suppresses directional energy transfer and promotes efficient hole tunneling injection from the adjacent organic photoresponse layer. Simultaneously, I/Br halogen gradient engineering is employed to precisely tune the bandgap, thereby enhancing optical performance and enabling selective detection at the target wavelength of 600 nm. The organic layer induces electron trapping and interfacial band bending, facilitating efficient hole tunneling injection at low bias. Consequently, the optimally designed PM‐NPDs with a segregated structure consist of a quasi‐2D perovskite layer coupled with an organic layer, achieving a peak EQE of 1200% and a D * of 1.82 × 10 11 Jones at a bias voltage of 3 V. Notably, the device incorporates a quasi‐2D perovskite layer with a thickness of 110 nm, which provides a critical foundation for the miniaturization and high‐density integration of portable and flexible optoelectronic devices.