3, Korea Institute of Science and Technology, Seoul, , Korea (the Republic of)
2, Seoul National University, Seoul, , Korea (the Republic of)
Although the efficiency of quantum dot (QD) light-emitting diodes (QLEDs) has been greatly improved recently as a result of remarkable advances in the QD synthesis and device engineering, the lifetime of QLEDs is still far behind the requirement of practical display applications. In order to improve the lifetime it is necessary to understand the intrinsic degradation mechanism of QLEDs and optimize the device structure. The performance of QLEDs is strongly affected by the balance of electrons and holes injected into the QD emissive layer. Unbalanced charge injection leads to poor efficiency and stability as well as efficiency roll-off at high current density due to Auger recombination. Here, we systematically studied the correlation between the device performance and charge transport properties of electron transport layer (ETL) and hole transport layer (HTL). We will demonstrate that the lifetime and efficiency of QLEDs can be enhanced through optimizing charge transport properties of ETL and HTL. Furthermore, we will show that the device lifetime increases significantly by reducing the leakage current at low bias voltage.