Enhanced Charging/Discharging Process in Perovskite Active Light Source for High‐Speed Visible‐Light Communication

Abstract Metal halide perovskites are promising light source materials for visible light communication (VLC) due to their excellent photoelectric properties and small resistance‐capacitance time constant. However, previous reports mainly used perovskites as the passive light sources, which not only makes it susceptible to posterior excitation light sources, but also complex in the integration process. Herein, the quasi‐2D PEA₂Cs_n‐1Pb_nBr_3n+1 perovskite light–emitting diodes (PeLEDs) as an active light source in VLC link is demonstrated. It is found that the charging/discharging process of PeLEDs is an important factor governing the ‐3 dB bandwidth (f_{‐3 dB}) of the VLC. To improve this, 3‐sulfopropyl methacrylate potassium salt (SMPS) molecules are introduced into perovskite to simultaneously passivate deep and shallow energy level defects at grain boundaries. Additionally, the multiple quantum wells structures of PEA₂Cs_n‐1Pb_nBr_3n+1 are modified to be flat. At the optimal SMPS concentration, the maximum external quantum efficiency of PeLEDs reaches 21.5%. Meanwhile, the VLC achieves 3.2 MHz f_{‐3 dB} with data transmission of 18.6 Mbps, which is the highest f_{‐3 dB} in PeLEDs with the same active area. Hence, it provides a versatile method to improve the performance of VLC links based on active light sources and advances toward the goal of high‐speed, energy‐efficient and secure free communication.