Development of high-efficiency near-infrared organic light-emitting diodes using TPA-DCPP via interface exciplex formation

Abstract

Near-infrared organic light-emitting diodes (NIR OLEDs) hold great promise for applications in biomedical imaging, optical communication, and night-vision technologies. However, their efficiencies remain limited by the intrinsically narrow bandgaps of NIR emitters and severe aggregation-caused quenching (ACQ). Here, a high-efficiency NIR OLED is demonstrated using an interfacial exciplex formed between CBP and PO-T2T as an energy-transfer medium to sensitize the NIR emitter TPA-DCPP. This interfacial exciplex strategy avoids the use of heavy-metal complexes and complex thermally activated delayed fluorescence molecular design, enabling a heavy-metal-free and structurally simple device concept. The exciplex exhibits efficient Förster resonance energy transfer (FRET) to the guest emitter due to the strong spectral overlap between its emission and the TPA-DCPP absorption band. Through systematic optimization of the device architecture—including transport-layer thickness and guest-doping concentration—the optimized OLED achieves a maximum external quantum efficiency (EQE_max) of 15.2% and a peak luminance of 2152 cd m⁻² at 700 nm. This work highlights the effectiveness of interfacial exciplex-mediated energy transfer in mitigating ACQ-induced efficiency losses, providing a straightforward and reproducible pathway toward high-performance, heavy-metal-free NIR OLEDs.