Self-Powered and Low-Noise Perovskite Photodetector Enabled by a Novel Dopant-Free Hole-Transport Material with Bottom Passivation for Underwater Blue Light Communications

Designing dopant-free hole-transport materials (HTMs) is a facile and effective strategy to realize highperformance organic-inorganic hybrid perovskite (OIHP) photo detectors. Herein, a novel phenothiazine polymer, poly[4-(10Hphenothiazin-10-yl)-N,N-bis(4-methoxyphenyl)aniline] (PPZTPA), was synthesized and employed as a promising HTM in OIHP photodetectors. The triphenylamine donor unit was combined with a phenothiazine core, furnishing the polymer with a suitable highest occupied molecular orbital level, favorable thermal stability, and appropriate film morphology. The sulfur atom in the phenothiazine functional group can intentionally passivate the undercoordinated Pb2+ of OIHP films, suppressing nonradiative recombination and yielding an ultralow dark current density of 1.26 x 10-7 A cm-2 under -0.1 V, as well as a low-noise current of 3.75 x 10-13 A Hz-1/2 at 70 Hz. Encouragingly, the self-powered PPZ-TPA-based OIHP photodetectors were successfully integrated into a blue light communication system for the first time, demonstrating their application for receiving and transmitting light signals with a transmission rate of 300 bps. In addition, the PPZ-TPA-based devices exhibit nearly 1 year shelf stability without obvious degradation. We believe that PPZ-TPA demonstrates great potential to achieve high-performance perovskite photodetectors, also providing a strategy for the design of novel HTMs.