Improved blue quantum dot light-emitting diodes via chlorine passivated ZnO nanoparticle layer

In blue quantum dot light emitting diodes(QLEDs),electron injection is insufficient,which would degrade device efficiency and stability.Herein,we employ chlorine passivated ZnO nanoparticles as electron transport layer to facilitate electron injection into QDs effectively.Moreover,it suppresses exciton quenching at the QD/ZnO interface by blocking charge transfer channel.As a result,the maximum external quantum efficiency of blue QLED was increased from 2.55%to 4.60%,and the operation lifetime of blue QLED was nearly 4 times longer than that of the control device.Our work indicates that election injection plays an important role in blue QLED efficiency and stability.

Enhancing performance of inverted quantum-dot light-emitting diodes based on a solution-processed hole transport layer via ligand treatment

The performance of inverted quantum-dot light-emitting diodes(QLEDs)based on solution-processed hole transport layers(HTLs)has been limited by the solvent-induced damage to the quantum dot(QD)layer during the spin-coating of the HTL.The lack of compatibility between the HTL’s solvent and the QD layer results in an uneven surface,which negatively impacts the overall device performance.In this work,we develop a novel method to solve this problem by modifying the QD film with 1,8-diaminooctane to improve the resistance of the QD layer for the HTL’s solvent.The uniform QD layer leads the inverted red QLED device to achieve a low turn-on voltage of 1.8 V,a high maximum luminance of 105500 cd/m2,and a remarkable maximum external quantum efficiency of 13.34%.This approach releases the considerable potential of HTL materials selection and offers a promising avenue for the development of high-performance inverted QLEDs.

A dC/dV Measurement for Quantum-Dot Light-Emitting Diodes

We present dC/dV analysis based on the capacitance-voltage(C–V)measurement of quantum-dot lightemitting diodes(QLEDs),and find that some key device operating parameters(electrical and optical turn-on voltage,peak capacitance,maximum efficiency)can be directly related to the turning points and maximum/minimum of the dC/dV(versus voltage)curve.By the dC/dV study,the behaviors such as low turn-on voltage,simultaneous electrical and optical turn-on process,and carrier accumulation during the device aging can be well explained.Moreover,we perform the C–V and dC/dV measurement of aged devices,and confirm that our dC/dV analysis is correct for them.Thus,our dC/dV analysis method can be applied universally for QLED devices.It provides an in-depth understanding of carrier dynamics in QLEDs through simple C–V measurement.