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.

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.

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.

Erratum to: On the voltage behavior of quantum dot light-emitting diode

Erratum to Nano Research,2023,16(4):5511–5516 https://doi.org/10.1007/s12274-022-5106-8 The title in the article was unfortunately mispresented on page 5511.The title of the article should be corrected to“On the voltage sweep behavior of quantum dot light-emitting diode”.Instead of On the voltage behavior of quantum dot light-emitting diode It should read On the voltage sweep behavior of quantum dot light-emitting diode.

On the voltage behavior of quantum dot light-emitting diode

The origin of the efficiency drop of quantum dot light-emitting diode(QLED)under consecutive voltage sweeps is still a puzzle.In this work,we report the voltage sweep behavior of QLED.We observed the efficiency drop of red QLED with ZnMgO electron transport layer(ETL)under consecutive voltage sweeps.In contrast,the efficiency increases for ZnO ETL device.By analyzing the electrical characteristics of both devices and surface traps of ZnMgO and ZnO nanoparticles,we found the efficiency drop of ZnMgO device is related to the hole leakage mediated by trap state on ZnMgO nanoparticles.For ZnO device,the efficiency raise is due to suppressed electron leakage.The hole leakage also causes rapid lifetime degradation of ZnMgO device.However,the efficiency and lifetime degradation of ZnMgO device can be eliminated with shelf aging.Our work reveals the distinct voltage sweep behavior of QLED based on different ETLs and may help to understand the lifetime degradation mechanism in QLED.