Energy-well band structure for enhanced exciton confinement effect in perovskite light-emitting diodes via spray-coating

Perovskites possess bright emission and high color purity, but constructing strong charge confinement is requisite for application in efficient light-emitting diodes. Here, we demonstrate a breakthrough to enhance the exciton confinement effect by introducing a Cs4PbBr6 layer on a CsPbBr3 perovskite film through the spray-coating deposition. The impact of the Cs4PbBr6 layer is thoroughly investigated and indicates that the Cs4PbBr6 layer results in a confined energy-wall band structure and a stronger exciton binding energy. Accordingly, the CsPbBr3 film with Cs4PbBr6 wall exhibits higher photoluminescence (PL) and electroluminescence (EL) from the perovskite light-emitting diodes (PeLEDs). We further optimize the device architecture in an energy-well band structure by sandwiching the CsPbBr3 between the Cs4PbBr6 buried layer and overlayer. As a result, the PeLED with Cs4PbBr6 well exhibits similar to 18 nm of full width at half maximum (FWHM) in the emission spectrum, 25,738 cd m(-2) of maximum luminance, 65.94 cd A(-1) of maximum current efficiency (CE), 15.08% of maximum external quantum efficiency (EQE).