Preferred Orientation and Phase Distribution of Quasi-2D Perovskite for Bifunctional Light-Emitting Photodetectors

In traditional optical wireless communication (OWC) systems, the simultaneous use of multiple sets of light-emitting diodes (LEDs) and photodetectors (PDs) increases the system complexity and instability. Here we report bifunctional light-emitting photodetectors (LEPDs) fabricated with quasi-2D perovskite (F-PEA)₂Cs₄Pb₅I₁₁Br₅ as light-emitting/detecting layers for efficient, miniaturized, and intelligent bidirectional OWC. By simply changing the solvent composition of the precursor solution and using antisolvent engineering, we manipulated the crystal orientation and phase distribution of (F-PEA)₂Cs₄Pb₅I₁₁Br₅, realizing high irradiance (4.36 μW cm^-2) and a -3 dB refresh rate (0.21 MHz) of electroluminescence in LED mode as well as low noise (below 1 pA Hz^-1/2) and high responsivity (0.1 A W^-1) in PD mode. The rapid and accurate OWC process was demonstrated through interaction of LEPDs. We also demonstrated the high-fidelity compression and digitization of high-resolution (256 × 256 pixels) color images using the four-step phase shift method to realize intelligent encrypted image OWC.