Improved performance of all-inorganic quantum-dot light-emitting diodes using an all-solution process at low temperatures†

Organic light-emitting diode (OLED) displays have widespread applications, but the inherent instability of the devices, such as burn-in, short lifetime and poor stability, remains a critical drawback. Herein, an all-inorganic quantum-dot light-emitting diode (QLED) is developed using an all-solution process method at a low temperature. The simple strategy is engineered by introducing repeated UV-ozone treatments during Mg–NiO layer spin coating to enhance hole injection in the QLED device. The fabricated conventional QLED shows an improved EQE of 3.73%, which is 2.2 times higher than that of the QLED without UV-ozone treatment. In addition, the inverted all-inorganic LED exhibits a maximum EQE of 2.63% with a luminance of 3640 cd m⁻². It can be concluded that UV-ozone treatment creates non-stoichiometry in NiO, resulting in Ni³⁺ vacancy defects, which lower the valence band of Mg–NiO and enhance hole injection.