Bidirectional Self‐Powered Perovskite Transient Photodetectors with Broadband Capabilities for Optical Wireless Communication

ABSTRACT High‐performance photodetectors are essential for advanced optical detection and communication technologies. Perovskite photodetectors (PPDs) have emerged as promising optoelectronic candidates owing to their high absorption, tunable band gaps, excellent carrier mobilities, and superior optoelectronic conversion efficiencies. Conventional Schottky‐type photodetectors often suffer from high dark current, low detectivity, and the requirement for external biasing. Here, we report a self‐powered, bidirectional, and structurally simple perovskite transient photodetector (PTPD) with the configuration of ITO/PEDOT:PSS/MAPbI 3 /PC 71 BM/BCP/Ionic Liquid/ITO. The device employs MAPbI 3 films synthesized via a hybrid two‐step method as the photoactive layer, while an ionic liquid serves as the dielectric medium. The incorporation of the ionic liquid facilitates the formation of electric double layers, thereby enhancing charge separation and improving sensitivity without any external bias. The PTPDs exhibit an enhanced transient response, with microsecond‐scale response times and high −3 dB cutoff frequencies of 0.86 MHz and 1.29 MHz for small (0.04 cm 2 )‐ and large (3.2 cm 2 ) ‐area devices, respectively, demonstrating outstanding performance. Furthermore, we establish an optical communication system based on ASCII coding, where UV, green, and red illumination are employed as carriers, and the developed devices function as optical signal receivers. These results highlight the potential of PTPDs for practical integration into next‐generation optical communication systems.