Developing TADF polymer as semiconductor additive for high performance perovskite light emitting diodes with dual recombination channel and small efficiency roll-off

Passivation of the defect of perovskite films while maintaining efficient carrier transporting and exciton utilization in grain boundaries remains a substantial challenge. Here, in contrast to previously insulated polymers, two semiconductor TADF polymers were designed and synthesized as functional additives for perovskite light emitting diodes (PeLEDs) for the first time. The measured trap-filled limited voltages indicate that TADF polymer can act as efficient additive to reduce the non-radiative transition of the perovskite by passivating the defect and suppressing the Auger recombination. Moreover, the detail characterizations also demonstrated that the optimized polymer structure with flexible wrapping units appears to be beneficial for enhancing hydrophobicity, thermal stability, uniform crystallinity and high photoluminescence of the perovskite. As a result, the TADF polymer-modified PeLEDs achieve a high current efficiency of 66.1 cd A-1 and an external quantum efficiency of 17.4% with small efficiency roll-off and high color purity. Comparing to the standard PeLEDs, the notably three times higher enhanced device efficiency and stability fully highlight the potential of semiconductor TADF polymer as a functional additive to further develop high-performance perovskite electroluminescence devices.