- 标题
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Suppressing Efficiency Roll-Off at High Current Densities for Ultra-Bright Green Perovskite Light-Emitting Diodes
摘要： Perovskite light-emitting diodes (PeLEDs) have undergone rapid development in the last several years with external quantum efficiencies (EQE) reaching over 21%. However, most PeLEDs still suffer from severe efficiency roll-off (droop) at high injection current densities, thus limiting their achievable brightness and presenting a challenge to their use in laser diode applications. In this work, we show that the roll-off characteristics of PeLEDs are affected by a combination of charge injection imbalance, nonradiative Auger recombination, and Joule heating. To realize ultrabright and efficient PeLEDs, several strategies have been applied. First, we designed an energy ladder to balance the electron and hole transport. Second, we optimized perovskite materials to possess reduced Auger recombination rates and improved carrier mobility. Third, we replaced glass substrates with sapphire substrates to better dissipate joule heat. Finally, by applying a current-focusing architecture, we achieved PeLEDs with a record luminance of 7.6 Mcd/m2. The devices can be operated at very high current densities (J) up to ~ 1 kA/cm2. Our work suggests a broad application prospect of perovskite materials for high-brightness LEDs and ultimately a potential for solution-processed electrically pumped laser diodes.
关键词： Joule heat,efficiency roll-off,Auger recombination,charge injection balance,high injection current density,ultrahigh brightness,perovskite light emitting diodes
更新于2025-09-23 15:19:57
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Ultrahigh brightness attosecond electron beams from intense X-ray laser driven plasma photocathode
摘要： The emerging intense attosecond X-ray lasers can extend the Laser Wakefield Acceleration mechanism to higher plasma densities in which the acceleration gradients are greatly enhanced. Here we present simulation results of high quality electron acceleration driven by intense attosecond X-ray laser pulses in liquid methane. Ultrahigh brightness electron beams can be generated with 5-dimensional beam brightness over 1020 A · m?2 · rad?2. The pulse duration of the electron bunch can be shorter than 20 as. Such unique electron sources can benefit research areas requiring crucial spatial and temporal resolutions.
关键词： attosecond X-ray lasers,ultrahigh brightness electron beams,liquid methane,Laser Wakefield Acceleration,5-dimensional beam brightness
更新于2025-09-16 10:30:52