Development and challenges of indium phosphide-based quantum-dot light-emitting diodes

Quantum dot light-emitting diodes (QLEDs) have developed rapidly in the last several decades, in which the maximum external quantum efficiency of the three primary color cadmium (Cd)-based QLEDs have exceeded the theoretical maximum value. However, the presence of Cd element has severely hampered their commercialization. Indium phosphide (InP)-based quantum dots (QDs) without heavy metals have continuously adjustable luminescence range from blue to near infrared, which is a competitive alternative for Cd-based QDs. Especially in the last few years, the synthesis techniques and the device structures of InP-based QLEDs have been greatly improved. In this review, we first introduce the properties of InP-based QDs, carrier dynamics and the early development history. Then, we focus on the development of InP-based red, green and blue primary color QLEDs from their first report in 2011 to the current state of the art. The effects of QDs structure (core/shell or gradient-alloyed QDs and organic ligand modified QDs) and device structure (charge transport layer and interfacial engineering) on the performance of InP-based QLEDs are also summarized.