Elongated grain morphology for efficient and radiant NIR-II Sn-based perovskite light-emitting diodes

Sn-based perovskite light-emitting diodes have attracted considerable attention due to their environmentally friendly properties and potential for second near-infrared window emission. However, intrinsic self-p-doping and high hole mobility of Sn-based perovskites lead to excessive hole injection under high current densities, causing severe hole dissipation and hindering the achievement of high efficiency at high radiance. Here, we present a grain morphology modulation strategy to optimize electron-hole injection and recombination dynamics. By introducing a growth regulator, perovskite grain morphology remarkably transforms from low-lying dendritic structures to elongated island-like formations, which restricts hole over-injection and spatially confines the recombination zone deeper into perovskite bulk. Consequently, optimal devices achieve an external quantum efficiency of 10.7% and a high radiance of 173 W sr^-1 m^-2, with NIR-II emission at 963 nm. Furthermore, the devices demonstrate low-efficiency roll-off, achieving an external quantum efficiency of 8.1% at a high radiance of 153.6 W sr^-1 m^-2.