Quantum dot light-emitting diodes with an Al-doped ZnO anode

Abstract

A study of hybrid ZnCdSeS/ZnS quantum dot light-emitting diodes (QLEDs) device fabricated with indium tin oxide-free transparent electrodes is presented. Al-doped zinc oxide (AZO) prepared by magnetron sputtering is adopted in anode transparent electrodes for green QLEDs with different sputtering pressures. A Kelvin probe force microscopy measurement showed that AZO has a work function of approximately 5.0 eV. The AZO/poly(ethylene-dioxythiophene)/polystyrenesulfonate (PEDOT:PSS) interface can be adjusted by the sputtering pressures, which was confirmed by hole-only devices. AZO films with low surface roughness can form a good AZO/PEDOT:PSS interface, which can increase the holes’ injection, and result in an improved charge balance. The maximum current efficiency, luminance, and external quantum efficiency of the optimized QLED devices under a sputtering pressure of 1 mTorr can achieve values of 50.75 cd A−1, 102 500 cd m−2, and 12.94%, respectively.

Influence of Sputtering Pressure on the Conductivity and Transparency of Aluminum-Doped Zinc Oxide Films

“…Additionally, AZO films are unique in that they can be obtained in a crystalline form at ambient temperature, setting them apart from other materials [5][6][7][8]. Therefore, AZO has many potential uses, including in surface acoustic wave devices [9], gas sensors [10], light-emitting diodes (LEDs) [11], and low emissivity films [12]. In addition, AZO films have been used as front TCOs and back reflector coating for highefficiency solar cells due to their high haze ratio for light scattering and light trapping [13].…”