Morphology control of CsPbBr₃ films by a surface active Lewis base for bright all-inorganic perovskite light-emitting diodes

All inorganic perovskites are regarded as promising candidates for light-emitting diodes (LEDs) due to their excellent luminescent properties and material stability. However, the film morphology of the perovskite emitting layer has a substantial effect on the device performance of perovskite LEDs (PeLEDs). Herein, we developed a facial method to optimize the film morphology of solution-processed CsPbBr₃ films by incorporating a Lewis base of caprylyl sulfobetaine (SB3-10) into the perovskite precursor. The interaction between SB3-10 molecules and metal ions in perovskites could retard the crystallization of the CsPbBr₃ film, producing a uniform film with a smooth surface morphology. In addition, the addition of SB3-10 could passivate the defects and traps in the perovskite layer to suppress the nonradiative recombination of the charge carriers. Consequently, the resulting CsPbBr₃:SB3-10 based PeLEDs presented a maximum external quantum efficiency of 2.3% with a bright luminance of 23 240 cd m⁻² and a maximum current efficiency of 8.45 cd A⁻¹. The finding in this work provides a better understanding of the role of SB3-10 based Lewis base in controlling the surface morphology of the CsPbBr₃ films.