Enabling Quasi‐2D Perovskite‐Compatible Growth Environment for Efficient Light‐Emitting Diodes

Abstract Despite the rapid advancement in electroluminescence efficiencies of perovskite light‐emitting diodes (PeLEDs), it remains challenging to achieve efficient and reproducible devices. Herein, an effective vapor‐assisted growth (VAG) method is proposed to develop quasi‐2D perovskite thin‐films via creating a saturated dimethyl sulfoxide vapor environment. The VAG‐optimized perovskite films with a composition of PEA₂(FAPbBr₃)_n−1PbBr₄ display uniformly distributed nanograins with graded energy landscape and compact surface, contributing to enhanced radiative and suppressed nonradiative recombination. Consequently, the PeLEDs incorporating VAG‐based films with a device architecture of indium tin oxide/poly(9,9‐dioctylfluorene‐alt‐N‐(4‐sec‐butylphenyl)‐diphenylamine)/perovskite/(1,3,5‐tris(phenyl‐2‐benzimidazolyl)benzene)/Yb/Ag demonstrate a peak current efficiency of 27.1 cd A⁻¹ (@ 532 nm) with an external quantum efficiency of 6.50% and a maximum luminance of 17 610 cd m⁻². Notably, champion PeLEDs manifest considerably curtailed efficiency roll‐off as ≈50% of the peak efficiency is preserved even at a very high luminance of 15 000 cd m⁻². Meanwhile, VAG‐based PeLEDs exhibit improved reproducibility compared to the control counterparts. It is anticipated that this work would promote the development of reliable solution‐processing methods toward stabilized perovskite‐based photonics.