Contents I. Introduction
Quantum-DOT emitting diode (QLED) has received intensive attention and is considered to be one of the most advantageous display technologies for the next generation due to its adjustable emission wavelength, narrow emission bandwidth, high quantum yield and good photochemical stability [1]–[11]. The emission layer (EML) of the QLED, which is sandwiched between two charge transport layers, easily interacts with the charge transport layers to cause the exciton quenching at the interface, thus decreasing the efficiency and lifetime of devices [12]–[14]. There are some viable reports by introducing various thin intermediate organic layers to decrease leakage current and suppress exciton quenching for higher performance, such as polyethylenimine (PEI), polyethylenimine ethoxylated (PEIE) and polymerthylmethacrylate (PMMA) [2], [13]–[15]. These functional layers can effectively balance carrier injection. However, these methods are still not satisfactory, because the direct spin coating of intervening interlayer on the surface of EML will cause the redissolving and damage of EML. In addition, the spin-coating process of the intervening layer has the disadvantage of uneven film formation, poor accuracy of film thickness and waste of materials [16], [17].
