Pasivación de bromuro de fosfonio cuaternario para diodos emisores de luz de puntos cuánticos de perovskita de alto...

Surface ligands are crucial for perovskite quantum dot (PQD) optoelectronics. However, long alkyl chains limit charge transport, while short chains destabilize their soft lattice, presenting a stability-mobility dilemma. Moreover, surface-bound protonated primary amines are susceptible to deprotonation, accelerating performance decay and structural collapse. In this work, we introduced tetrabutylphosphonium bromide (TBPB) as a surface passivation ligand to overcome these limitations. TBPB combines minimal molecular polarity-enabling a short chain for superior charge transport-with a fully coordinated phosphonium center that resists deprotonation and passivates halogen vacancies. This yields quantum dots with near-unity PLQY and robust stability, leading to LEDs achieving a maximum external quantum efficiency (EQE) of 24.28% and luminance of 122,786 cd m^-2, far surpassing control devices. Further shortening the ligand chain increases EQE to 27.89% but at the cost of severe luminance loss, underscoring the delicate balance in ligand engineering.