2D Perovskite/Organic Heterojunction Black‐Light Level Photodetector with Record‐High Detectivity

Abstract 2D single‐crystal perovskites have attracted interest due to their excellent photoelectric properties and improved moisture stability, making them promising for various optoelectronic applications. However, challenges remain, particularly low carrier collection efficiency caused by high exciton binding energy. This study introduces self‐powered heterojunction photodetectors (PDs) based on (PEA) 2 PbI 4 /ZnPc, enhancing carrier conduction by the configuration of lateral electrodes and regulating carrier/exciton dynamics via the heterojunction design. The PD achieves an impressive detectivity of 1.14 × 10 16 Jones, a 770% increase compared to the control, with a detection limit reaching the black‐light level of 3 pW cm −2 under 532 nm at 1 V bias. This performance surpasses all previously reported 2D perovskite PDs and is attributed to suppressed dark current and increased photocurrent. The built‐in electric field at the heterojunction counteracts part of the forward bias, reducing intrinsic carrier motion in (PEA) 2 PbI 4 in the dark. It also effectively dissociates photogenerated excitons, minimizing radiative recombination under illumination. This allows the device to detect weak light at the black‐light level in self‐driven mode. Additionally, the heterojunction device extends the detectable wavelength to 980 nm. This PD has been successfully applied in acousto‐optic conversion communication, highlighting its potential for low‐power, energy‐efficient optical communication solutions.