Self-powered and charge-transport-layer-free photodetectors based on chloride treated perovskites for weak light detection

Organic-inorganic halide perovskite materials have been widely used in photodetectors (PDs) for the solution processability and outstanding optoelectronic characteristics. However, conventional perovskite-based PDs normally require both electron transport materials and hole transport materials to provide sufficient driving forces for separating the hole-electron pairs while concurrently enhancing the processing consumption. In this study, the high-performance self-powered PDs without charge transport layers based on phenyltrimethylammonium chloride (PTACl)-treated perovskite are fabricated via a simple solution process. The triple-cation mixed halides perovskite (CsFAMA)Pb(BrI)₃ acts the photo active layer for its uneven distribution vertically, which will provide the driving forces for charge separation and transportation. With the treatment of PTACl, the charge separation and transportation are further accelerated, which has been proved by electrochemical impedance spectroscopy and Mott-Schottky measurements. Therefore, the PDs can still achieve outstanding photodetection performance, even under the self-powered operation mode, including the I_light/I_dark ratio up to 1.8 × 10⁵, responsivity up to 198 mA W⁻¹, and detectivity up to 1.48 × 10¹³/1.24 × 10¹¹ Jones (calculated by dark/noise current methods). More significantly, the devices can exhibit an obvious response to weak light of 0.64 nW cm⁻², and a PD array is also fabricated to verify the weak light detection capability. Furthermore, the PDs without any encapsulation exhibit excellent air stability during a 700-h test. Our realization of self-powered perovskite-based PDs offers a simple and feasible pathway toward the development of weak light detection.