Suppressed phase separation in blue perovskite light-emitting diodes with Rb doping

Metal halide perovskites possess high photoluminescence quantum efficiency, efficient charge carrier mobility, and solution-processability, and have been widely used in solid-state light-emitting diodes (LEDs). In a relatively short development period, these materials have progressed rapidly, attaining EQEs above 20% across the near-infrared, red, and green wavelengths. However, blue PeLEDs still exhibit considerably lower performance in comparison to other wavelengths and illustrate low operational spectrum stability. This study demonstrates that by modifying the perovskite precursor composition, partially replacing cesium (Cs) with rubidium (Rb), and optimizing the device structure, phase segregation was effectively suppressed, also the electroluminescence wavelength is shorter than that without Rb doping. As a result, we obtained blue PeLEDs (473nm) with a peak EQE of 0.6%, and the resultant device shows improved phase stability during the operation.