High-Performance Organic Upconversion Devices Based on Exciplex Emitters for Near-Infrared Visualization in...

Organic upconversion devices (OUPCs) that convert near-infrared (NIR) photons into visible emission offer a promising platform for NIR visualization and detection, yet their practical deployment is hindered by high turn-on voltages and strong sensitivity to emitter composition. Here, we report a three-channel exciplex emitter architecture that enables low-voltage, emitter compositional-tolerant OUPCs. Benefiting from synergistic multichannel energy transfer and efficient reverse intersystem crossing within the exciplex system, the light-emitting unit exhibits a low turn-on voltage of 2.3 V and a maximum external quantum efficiency of 18%. Notably, nearly invariant emission performance is maintained over a wide D:A ratio range (DBT-SADF:PO-T2T from 2:8 to 8:2), with coefficients of variation of 0.11 for external quantum efficiency, indicating good processing tolerance. Based on this emitter, the resulting OUPC achieves an ultralow upconversion turn-on voltage of 1.6 V under 850 nm excitation, a maximum luminance on:off ratio exceeding 3.1 × 10⁶, a detectivity of more than 1.5 × 10¹³ Jones, and visible emission (3 cd/m²) even at a weak NIR power density of 7 μW/cm². Benefiting from the high-performance OUPC, we successfully achieved encrypted image decryption and bioimaging. These findings demonstrate that the proposed exciplex emitter strategy not only eliminates the reliance on heavy-metal emitters but also simultaneously enhances device performance and application potential, providing a scalable approach for NIR information visualization.