Mitigation of Nonradiative Recombination by Reconfiguring Triplet Energy of Additive Toward Efficient Blue Perovskite Light-Emitting Diodes

The exceptional optoelectronic properties of metal halide perovskites, including enhanced color saturation and tunable emission wavelengths, render them highly potential candidates for fabricating perovskite light-emitting diodes (PeLEDs). However, blue PeLEDs underperform relative to their red and green counterparts due to substantial nonradiative recombination losses, particularly at the perovskite/electron transporting layer (ETL) interface. Here, we propose an effective energy management strategy aimed at boosting the efficiency of blue PeLEDs by the incorporation of a multifunctional interlayer, specifically 2,8-bis(diphenylphosphoryl)dibenzo[b,d]furan (PPF), at the perovskite/ETL interface. This approach involves the formation of robust P═O/Pb bonds between PPF and perovskite surface defects, thereby effectively mitigating trap-induced nonradiative recombination. Furthermore, the high triplet energy level of PPF inhibits triplet energy transfer from the perovskite to the ETL, leading to further reductions in energy loss. Consequently, the optimized blue PeLEDs exhibit a peak external quantum efficiency (EQE) of 15.1% (peak emission at 472 nm) with a 4-fold increased operational lifetime compared to the control PeLED. Additionally, utilizing blue PeLED units treated with PPF, we achieve a record EQE of 31.1% for hybrid perovskite/organic tandem white LEDs, which exhibit a high color rendering index of 85.