Highly stable quantum dot light-emitting diodes with improved interface contacting via violet irradiation

The relatively low stability of quantum dot light-emitting diodes (QLEDs) caused by unbalanced carrier injection has not been completely solved. Among various influencing factors, interface contacting is one of the important factors affecting the carrier injection equilibrium. Herein, we proposed a method to improve the carrier injection equilibrium for QLEDs. We investigated and explored the effects of violet irradiation on the efficiency and operating stability of MoO3-based inverted QLEDs. Specifically, violet irradiation on the interface of MoO3/Mg:Ag is carefully analysed. Further research shows that the interfacial reaction between Mg:Ag anode and MoO3 hole injection layer accounts for such improvement. During violet irradiation, the Mg:Ag quickly reacts with the oxygen from MoO3, leading to the formation of Mo-O-Mg:Ag interlayer. The hole injection is effectively enhanced, resulting from the reduction of the electrons extraction barrier at MoO3/Mg:Ag interface and the improvement of the interface contacting. By optimizing the violet irradiation dosage and violet wavelength, the maximum current efficiency (CE) is increased from 20.2 cd/A to 31.1 cd/A. Moreover, devices exhibit a highly stable operation lifetime of 44161 h (T95@1000 nits), which is much longer than non-violet irradiation QLEDs and meet the stringent industrial requirements for display applications.