Entropy–Enthalpy Synergistic Quinary A-Site Engineering for High-Luminance and Stable Green Perovskite Light-Emitting Diodes

Abstract Multicomponent A-site engineering is effective in enhancing perovskite crystallization and optoelectronic performance, yet the cooperative mechanism of different cations in regulating crystallization kinetics remains unclear. Here, we propose an entropy–enthalpy synergistic quinary A-site strategy to modulate the crystallization of green 3D perovskites. By sequentially incorporating MA+, GA+, Cs+, and Rb+ into FAPbBr3, we constructed binary to quinary systems. This approach synergistically lowers the Gibbs free energy (ΔG), strengthens the thermodynamic driving force, and reduces the nucleation barrier (ΔG*), leading to dense and uniform nucleation as well as optimized crystal growth. The quinary device achieves a maximum luminance of 222,973 cd m–2 and maintains an External Quantum Efficiency (EQE) above 8% across 30,000–170,000 cd m–2. The peak luminance and maximum EQE are improved by approximately 12-fold and 20-fold, respectively, compared to the unary control. The device also exhibits an operational half-lifetime (T50) of 80 min at 13,000 cd m–2, corresponding to a projected lifetime of 1.47 × 104 h at 100 cd m–2. This work elucidates the synergistic role of multicomponent A-site cations in crystallization control and offers a promising route toward high-luminance brightness and stable 3D Perovskite Light-Emitting Diodes (PeLEDs).