Sol-gel processed tungsten trioxide nanocrystals layer for efficient hole-injection in quantum dot light-emitting diodes

Highlight• WO₃ film prepared on quartz by sol-gel route using W and H₂O_2. • WO₃ film on quartz substrate has transparency higher than 80%. • WO₃ film used as hole transport layer in quantum dot light-emitting diodes. • WO₃ film-based device performance was enhanced compared with PEDOT:PSS. In this work, we report highly bright and efficient quantum dot light-emitting diodes (QLEDs) using tungsten trioxide (WO₃) nanocrystals (NCs) thin film as hole-injection layers (HIL). The WO₃ thin film is prepared by a simple sol-gel method using W powder and H₂O₂ as precursors, stirring vigorously at room temperature, followed by calcinations at 420 °C for 1 h. The WO₃ thin film is compact and smooth, enabling the formation of HIL in green QLED. The luminance, current efficiency and operational lifetime of the QLED is 18560 cd m⁻², 11.8 cd A⁻¹ and 11844 h, respectively.