Dual Regulation of Crystallization Behavior and Hole Transport Capability Enables Efficient Pure-Red Tin-Based Perovskite Light-Emitting Diodes

Tin (Sn)-based perovskite light-emitting diodes (Sn-PeLEDs) have demonstrated great potential in next-generation displays and lighting fields, yet their performance is restricted by uncontrolled crystallization and the low hole-mobility/hydrophobic nature of the classic hole transport layer (HTL) materials, such as poly(9-vinylcarbazole) (PVK). In this work, we propose a dual-modification strategy that simultaneously governs the crystallization behavior and hole transport capability. An ultrathin interlayer of 2,7-bis(diphenylphosphoryl)-9,9'-spirobi[fluorene] (SPPO13) is inserted between perovskites and PVK to passivate defects at the perovskite bottom surface, while 4,4'-cyclohexylidenebis[<i>N</i>,<i>N</i>-bis(4-methylphenyl)benzenamine] (TAPC) is incorporated into PVK to increase its conductivity and hole mobility. The synergistic effect of SPPO13 and TAPC not only enhances the wettability of PVK but also optimizes the morphology of perovskite films, suppresses nonradiative recombination, and increases carrier recombination efficiency. By optimizing the concentrations of SPPO13 and TAPC, the Sn-PeLEDs reached a maximum luminance (<i>L</i>_max) of 161.30 cd/m², a maximum external quantum efficiency (EQE_max) of 0.28%, and a half lifetime (<i>T</i>₅₀) of 932 s, which were nearly 5.2, 2.3, and 2.7 times compared to the control device (<i>L</i>_max is 31.00 cd/m², EQE_max is 0.12%, and <i>T</i>₅₀ is 340 s), respectively. Meanwhile, the optimized device exhibits a low turn-on voltage of 2.63 V, a stable electroluminescence emission peak at 628 nm, and Commission Internationale de l'Éclairage (CIE) coordinates of (0.69, 0.30), which meet the BT.2020 red standard. This strategy offers a universal route toward high-performance Sn-PeLEDs.