Modulated Crystallization and Carrier Transport Properties for Green Perovskite Light-Emitting Diodes via Thermally Activated Delayed Fluorescent-Modified Hole Transport Layers

Efficient and stable green emission of perovskite light-emitting diodes (PeLEDs) is an essential element for their potential applications in full-color displays and solid-state lighting, aspiring to become a new generation of light-emitting devices. Rational manipulation of the entire electroluminescence process is expected to prepare high-performance devices. Hence, to generate effective green PeLEDs that simultaneously reduce energy loss during electron–photon conversion and increase light outcoupling, a simple device architecture is suggested. Consequently, in our research, we utilized thermally activated delayed fluorescent materials DTC-mBPSB and BTBC-DPS to modify the hole transport layer. Employing efficient interfacial engineering to modulate the growth of perovskite crystals resulted in dense perovskite films and effectively reduced the density of defective states by providing lone electron pairs to neutralize unsaturated Pb2+ via oxygen atoms in the passivation group of the S═O bond. Furthermore, this approach increases the carrier transport abilities and thus facilitates the occurrence of more radiative recombination. Hence, this approach contributes to the realization of EQE of 11.04% (DTC-mBPSB) and 13.97% (BTBC-DPS), respectively, for green PeLEDs emitted at 512 nm and enhances the operational stability, establishing a foundation for subsequent studies.