Electric field-induced segregation in a sky-blue perovskite light-emitting diode based on CsPbBr2Cl:PEO composite

Abstract Perovskite light-emitting diodes (pero-LEDs) is a rapidly developing technology that is supposed to supersede existing ones in the near future. In comparison with organic and A III B V analogues, pero-LEDs possess the following advantages: very narrow spectral linewidth of electroluminescence (EL), spectral tunability in the whole visible range and the possibility of a cost-effective large-scale fabrication by means of wet chemistry techniques. CsPbX 3 (X = Cl, Br, I) are the most robust perovskites suitable for LEDs production due to their excellent optical properties. There are numerous reports describing green and red electroluminescence of such tribromide and triiodide materials, respectively, whereas a blue color is not easy to achieve. The main obstacles in the way of development of blue pero-LEDs based on chlorine salts are poor solubility of perovskite precursors in the same organic solvents as well as light- and an electric field-induced phase instability of mixed-halide (CsPbBr 3− x Cl x ) materials. The latter leads to red-shift of EL spectrum with the increase in applied voltage. In this work, we present a design of a single-layer sky-blue pero-LED based on CsPbBr 2 Cl-poly(ethylene oxide) (PEO) thin film, study the morphology of the emissive layer, its phase instability under UV illumination and in the electric field.