Synergistic Interfacial Engineering Enables High-Performance Perovskite LEDs for High-Speed Visible Light Communication

Metal halide perovskite light-emitting diodes (PeLEDs) are emerging candidates for visible light communication (VLC), yet practical application remains hindered by imbalanced charge injection and interfacial defects, which limit the modulation bandwidth and overall VLC performance. The role of interfacial engineering in addressing these challenges remains insufficiently explored. Herein, we propose a multifunctional interfacial strategy using zwitterionic betaine citrate (BC) to simultaneously passivate defects and balance the charge injection. BC coordinates with Pb2+ to reduce traps and ionically interacts with PEDOT:PSS to lower the hole injection barrier, while methanol treatment improves interfacial contact and conductivity. These synergistic effects suppress nonradiative losses and reduce the resistance–capacitance (RC) time constant. As a result, PeLEDs achieve a 4.9 MHz modulation bandwidth and a 55.56 Mbps data rate, representing the best-reported performance for comparable device areas. This work highlights the importance of interfacial engineering in improving VLC performance and offers a practical pathway toward high-speed PeLED-based VLC.