Performance enhancement of CsPbBr₃ thin film-based light-emitting diodes by CsF-induced surface modification

Metal halide perovskites have been an attractive optoelectronic material for light-emitting diodes (LEDs) and display applications as well as photovoltaic devices. However, poor device performance and operation stability still impede their development and application. This paper reports a facile surface modification method to enhance the performance of CsPbBr₃ thin film-based LEDs using CsF with various molar contents. Structural and chemical investigations showed that the CsF treatment removes the surface pinhole defects and fluorinates the CsPbBr₃ surface simultaneously, which resulted in the enhanced photoluminescence intensity compared to the pristine one. The CsF treatment enhanced the LED performance by increasing the electroluminescence intensity while mitigating the saturation behavior, even under high applied bias. These outcomes were attributed to the advantageous roles of the CsF treatment, i.e., removal of surface pinhole defects, passivation of surface non-radiative defects, and the formation of an electron blocking layer.