Current Applied Physics, Vol.20, No.2, 366-370, 2020
Improvement of the electron transport behavior in quantum-dot light-emitting diodes using a low-temperature processable ZnO
Zinc oxide (ZnO) is a commonly used electron transport layer in quantum-dot light-emitting diodes (QLEDs). In this study, we used a highly conducive ZnO film via a low-temperature process to improve the electron transport behavior of the QLEDs. The electron transport behavior of ZnO film was investigated from the electron only device, and the origin of high conductivity was figured out using x-ray photoelectron spectroscopy. We found that the oxygen vacancy, which can improve the carrier transport in ZnO film, was increased according to reduce the process temperature of ZnO. Meanwhile, the hydroxyl group, which contribute to the quenching effect, was decreased according to reduce the process temperature of ZnO. Therefore, high-performance QLEDs were fabricated using the low-temperature processed ZnO, and it showed an improved luminance and current efficiency in a full current range. The maximum luminance and current efficiency of the devices were measured as 65,391 Cd/m(2) and 2.48 Cd/A, respectively. Moreover, the lifetime of the device was improved due to the low-temperature process. Therefore, we suggest that a highly conducive ZnO film could be formed through a low-temperature process, and it can improve the performance of QLEDs.