An investigation on the cyclic temperature-dependent performance behaviors of ultrabright air-stable QLEDs

Abstract

The aerobic and thermal stability of quantum-dot light-emitting diodes (QLEDs) is an important factor for the practical applications of these devices under harsh environmental conditions. We demonstrate all-solution-processed amber QLEDs with an external quantum efficiency (EQE) of > 14% with almost negligible efficiency roll-off (droop) and a peak brightness of > 600,000 cd/m2, unprecedented for QLEDs fabricated under ambient air conditions. We investigate the device efficiency and brightness level at a temperature range between − 10 and 85 °C in a 5-step cooling/heating cycle. We conducted the experiments at brightness levels higher than 10,000 cd/m2, required for outdoor lighting applications. Our device performance proves thermal stability, with minimal standard deviation in the performance parameters. Interestingly, the device efficiency parameters recover to the initial values upon returning to room temperature. The variations in the performance are correlated with the modification of charge transport characteristics and induced radiative/non-radiative exciton relaxation dynamics at different temperatures. Being complementary to previous studies on the subject, the present work is expected to shed light on the potential feasibility of realizing aerobic-stable ultrabright droop-free QLEDs and encourage further research for solid-state lighting applications.

New Solution of the Grain Boundary Grooving Problem in Polycrystalline Thin Films when Evaporation and Diffusion meet in Power Electronic Devices

“…It was found that the boundary conditions proposed by Mullins [12,13] and Amram et al [54] gave very large difference between the two solutions. Figure 7 showed that the maximum of the groove with the boundary conditions of Amram et al was four times smaller than that obtained by using the boundary conditions of Mullins, whereas the grain groove deep was twice deeper than that of Mullins's conditions.…”

“…In power semiconductor devices and modules, such as insulated gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs), thermal stress arises from the operation and dissipation of heat during switching events and continuous operation [7][8][9][10][11][12]. The cyclic nature of these temperature fluctuations subjects thin films within the devices to mechanical strain, leading to fatigue-related phenomena [13]. Groove formation, a characteristic manifestation of thermal stress, can occur on the surfaces of critical components such as substrates, interconnects, and Disclaimer/Publisher's Note: The statements, opinions, and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s).…”

Recent progress and opportunities in 2D-material quantum dots: synthesis, doping, characterization, and applications

“…The quantum dots narrow emission line widths achieved by electron-phonon coupling yielding higher purity colors for displays, tunable emission, minimum scattering in the visible region, and simple design fabrication are some of the vital characteristics making Quantum dots Light Emitting Diodes (QLEDs), the future, [158] and the urge to use the metal-free materials, the research interest is focussed on these 2D derived QDs. Temperature plays a crucial role in the performance of QLEDs as it could affect their stability, efficiency, and lifetime [159], making thermal control a major concern in QLEDs. A temperature-dependant study was carried out on MoS 2 QDs-based QLEDs, where a slight decrease of electroluminescence (EL) intensity with increased temperature depicted their stability at elevated temperatures (10-350 K) [160].…”

A New Solution to the Grain Boundary Grooving Problem in Polycrystalline Thin Films When Evaporation and Diffusion Meet in Power Electronic Devices

“…It was found that the boundary conditions proposed by Mullins [ 12 , 13 ] and Amram et al [ 64 ] gave a very large difference between the two solutions. Figure 7 showed that the maximum of the groove with the boundary conditions of Amram et al [ 64 ] was four times smaller than that obtained by using the boundary conditions of Mullins, whereas the grain groove deep was twice deeper than that of Mullins’s conditions.…”

“…In power semiconductor devices and modules, such as insulated gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs), thermal stress arises from the operation and dissipation of heat during switching events and continuous operation [ 7 , 8 , 9 , 10 , 11 , 12 ]. The cyclic nature of these temperature fluctuations subjects thin films within the devices to mechanical strain, leading to fatigue-related phenomena [ 13 ]. Groove formation, a characteristic manifestation of thermal stress, can occur on the surfaces of critical components such as substrates, interconnects, and passivation layers [ 14 , 15 , 16 ].…”