Quantum Dot Display Science and Technology

Chapter 8CdSe-based Quantum Dot Light-emitting Diodes

Yiran Yan, Longjia Wu, Weiran Cao, Xiaolin Yan

TCL Corporate Research, Nanshan District, Shenzhen, China

8.1 Overview of Quantum Dot Light-emitting Diode Development

Colloidal quantum dots (CQDs) have been considered one of the most promising phosphor materials for next-generation displays, lighting, and laser applications. CQDs can be optically or electrically excited to emit light. The former is a passive luminescence, and the latter is an active phenomenon in which electrons and holes are injected into the quantum dot (QD) emissive layer (EML) to form excitons. The QD light-emitting diode (QD-LED) technology can potentially offer extremely competitive advantages in display applications, including high-power conversion efficiency, ultra-pure color, fast response, as well as compatibility with large-scale solution fabrication processes and device flexibility.

The common device structure of QD-LEDs contains a hole injection layer (HIL), a hole transport layer (HTL), an EML, an electron transport layer (ETL), and electrodes. Holes and electrons are injected into the valence band of the HTL and the conduction band of the ETL from the anode and the cathode, respectively, generating excitons, followed by radiative decay to emit photons (Figure 8.1a) [1]. The device structure was rather simple when the QD-LED was first introduced in 1994, with only two functional layers: p-paraphenylene vinylene as the charge-transporting layer ...