Multifunctional TADF Additives for High-Performance Green Perovskite Light-Emitting Diodes

Quasi-2D metal halide perovskites are highly promising next-generation luminescent materials with extremely favorable photoelectric characteristics. Nevertheless, the photoelectric performance and stability of perovskite light-emitting diodes could potentially be seriously impacted by the inefficient energy transfer arising from the coexistence of multidimensional phases and the presence of a significant number of defects at perovskite grain boundaries or interfaces. In the present research, to address these challenges, modification of the light-emitting layer utilizing the thermally activated delayed fluorescent (TADF) materials of DTC-mBPSB and BTBC-DPS was achieved. These materials effectively suppress the small n-phase, while the Fo''rster channel efficiently facilitates the transfer of energy and carriers to the large n-phase, promoting radiative recombination. Additionally, the uncoordinated Pb2+ defects can be effectively passivated by the passivation group (S=O), resulting in a notable reduction in nonradiative recombination losses. This comprehensive approach, encompassing energy transfer optimization, balanced carrier transport, improved film morphology, and defect passivation, exhibits excellent effectiveness. As a result, we have achieved outstanding device performance, with current efficiencies (and EQE values) of 44.72 cd/A (DTC-mBPSB, EQE = 11.77%) and 68.18 cd/A (BTBC-DPS, EQE = 17.94%), correspondingly.