A review on the electroluminescence properties of quantum-dot light-emitting diodes

Quantum-dot light-emitting diodes (QLEDs) are unarguably the most successful member of rapidly developing family of devices based on quantum dots (type II−VI group compounds). Herein, the electroluminescence properties and fabrication/characterization technologies of QLEDs are reviewed. Particular emphasis is devoted to the dynamic processes of charge carriers and the related characterization technology because QLEDs are electro-optic conversion devices whose performance is to a great extent determined by the carrier transport/distribution and exciton formation. The utility of spectroscopic technologies, including steady/transient electroluminescence and photoluminescence, electro-absorption spectrum, and differential absorption spectrum are explained. Additionally, displacement current measurement technology is also discussed due to its potential to characterize the trapped charges within the devices. The strategies to improve the device performance by interface modification and QD design are summarized and the corresponding physics and chemistry mechanisms are discussed. Finally, a summary and outlook are shown about the challenge faced by QLED, as well as possible pathway to enhancing the device performance.