Morphology Controlled Nanocrystalline CsPbBr3 Thin-film for Metal Halide Perovskite Light Emitting Diodes

Abstract Morphology and crystal grain size of inorganic CsPbBr3 metal halide perovskite (MHP) films are controllable through a diffusion-controlled anti-solvent dripping crystallization method using an anti-solvent mixture of toluene (Tol):isopropanol (IPA). The 8:2 (v:v) Tol:IPA anti-solvent enables the production of a pinhole-free CsPbBr3 MHP film with the smallest crystal grain size and the brightest photoluminescence (PL). Accordingly, the 8:2 CsPbBr3 MHP film reveals a very uniform and strong PL mapping image. As a result, the 8:2 CsPbBr3 MHP light emitting diode (LED) exhibits ∼12.8, ∼7.4, and ∼7.9 fold enhanced maximum electroluminescence (ELmax), current efficiency (CEmax), and external quantum efficiency (EQEmax) compared to the 10:0 pristine device. The optimized 8:2 MHP LED shows an ELmax of 22298 cd/m2, CEmax of 36.65 cd/A and EQEmax of 9.64 %, respectively. In addition, the 8:2 CsPbBr3 MHP LED with controlled morphology and grain size has better operating stability than the pristine device.