High-Efficiency Top-Emitting Near-Infrared Organic Light-Emitting Diodes with Enhanced Outcoupling Efficiency

Currently, the performance of near-infrared (NIR) organic light-emitting diodes (OLEDs) still lags behind that of their visible-light counterparts. One key issue is the limited outcoupling efficiency due to the configuration of current NIR OLEDs. Here, efficient top-emitting (TE) NIR OLEDs are designed and prepared through precise adjustment of the organic microcavity, thereby incorporating a platinum-based emitter. By optimizing the doping concentration, several bimolecular annihilation processes, such as triplet‒triplet annihilation and triplet‒polaron annihilation, that occur in the NIR emitter can be modulated, thus reducing the roll-off efficiency. By incorporating the optimized emitting layer into the TE structure, a 47.6% outcoupling efficiency is obtained, which is determined by analyzing its power dissipation characteristics, and a 10% improvement in the quantum efficiency of the NIR emitter is achieved due to an increase in the radiative transition rate. As a result, these advancements yield NIR OLEDs that exhibit maximum external quantum efficiencies (EQEs) of 16.2% at a peak wavelength (λmax) of 701 nm and 14.9% at a λmax of 709 nm, nearly double the efficiency of bottom-emitting reference devices. These efficiencies set new records for NIR OLEDs with similar emission wavelengths.