Antisolvent-assisted surface engineering of quasi-2D perovskites with a TADF molecule for efficient green light-emitting diodes

A multifunctional TADF molecule DMAC-DPS was introduced through antisolvent-assisted post-treatment to achieve in situ surface engineering of quasi-2D perovskite films. • The sulfone (S O) groups in DMAC-DPS strongly coordinate with undercoordinated Pb²⁺ ions at the perovskite surface and grain boundaries, reducing deep-level defects and nonradiative recombination. • DMAC-DPS modulates the surface potential, optimizes energy-level alignment, balances charge injection, and suppresses leakage current and ion migration. Consequently, the maximum external quantum efficiency increases from 9.0% to 24.21%. Metal-halide perovskites have emerged as promising emitters for next-generation light-emitting diodes owing to their outstanding optoelectronic properties. Surface and interfacial defects are critical bottlenecks limiting the commercialization of metal halide perovskite light-emitting diodes (PeLEDs). In this work, a multifunctional thermally activated delayed fluorescence (TADF) molecule, bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS), was introduced via antisolvent-assisted post-treatment to realize in situ surface engineering of quasi-two-dimensional PEA₂Csₙ₋₁PbₙBr₃ₙ₊₁ perovskite emissive layers.The results show that the S O in DMAC-DPS forms strong coordination interactions with undercoordinated Pb 2 + species on the perovskite surface, leading to effective defect passivation. Meanwhile, post-treatment triggers secondary crystallization of perovskite films, which endows the film with enlarged grain size, reduced grain boundary density, and optimized crystallinity, albeit with a slight increase in surface roughness. Benefiting from the superior morphological and crystalline properties, the modified films deliver strengthened photoluminescence emission, extended carrier lifetime and inhibited non-radiative recombination. Further interfacial characterizations demonstrate that the DMAC-DPS modifier effectively regulates surface potential, optimizes energy level alignment, facilitates balanced charge injection, and simultaneously suppresses leakage current as well as detrimental ion migration. As a result, the maximum external quantum efficiency of the PeLEDs increases markedly from 9.0% to 24.21%, accompanied by a reduced turn-on voltage, enhanced luminance, and improved spectral stability. This work presents a facile and effective interfacial-engineering strategy based on antisolvent post-treatment, providing useful guidance for the development of efficient and stable green PeLEDs. Download: Download high-res image (140KB) Download: Download full-size image