共查询到20条相似文献,搜索用时 0 毫秒
1.
Zhaolong Chen Zhiqiang Liu Tongbo Wei Shenyuan Yang Zhipeng Dou Yunyu Wang Haina Ci Hongliang Chang Yue Qi Jianchang Yan Junxi Wang Yanfeng Zhang Peng Gao Jinmin Li Zhongfan Liu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(23)
The growth of single‐crystal III‐nitride films with a low stress and dislocation density is crucial for the semiconductor industry. In particular, AlN‐derived deep‐ultraviolet light‐emitting diodes (DUV‐LEDs) have important applications in microelectronic technologies and environmental sciences but are still limited by large lattice and thermal mismatches between the epilayer and substrate. Here, the quasi‐van der Waals epitaxial (QvdWE) growth of high‐quality AlN films on graphene/sapphire substrates is reported and their application in high‐performance DUV‐LEDs is demonstrated. Guided by density functional theory calculations, it is found that pyrrolic nitrogen in graphene introduced by a plasma treatment greatly facilitates the AlN nucleation and enables fast growth of a mirror‐smooth single‐crystal film in a very short time of ≈0.5 h (≈50% decrease compared with the conventional process), thus leading to a largely reduced cost. Additionally, graphene effectively releases the biaxial stress (0.11 GPa) and reduces the dislocation density in the epilayer. The as‐fabricated DUV‐LED shows a low turn‐on voltage, good reliability, and high output power. This study may provide a revolutionary technology for the epitaxial growth of AlN films and provide opportunities for scalable applications of graphene films. 相似文献
2.
3.
4.
5.
Highly Efficient Perovskite Nanocrystal Light‐Emitting Diodes Enabled by a Universal Crosslinking Method 下载免费PDF全文
Guangru Li Florencia Wisnivesky Rocca Rivarola Nathaniel J. L. K. Davis Sai Bai Tom C. Jellicoe Francisco de la Peña Shaocong Hou Caterina Ducati Feng Gao Richard H. Friend Neil C. Greenham Zhi‐Kuang Tan 《Advanced materials (Deerfield Beach, Fla.)》2016,28(18):3528-3534
6.
7.
8.
9.
10.
11.
Yang Shen Li‐Peng Cheng Yan‐Qing Li Wei Li Jing‐De Chen Shuit‐Tong Lee Jian‐Xin Tang 《Advanced materials (Deerfield Beach, Fla.)》2019,31(24)
Perovskite light‐emitting diodes (PeLEDs) show great application potential in high‐quality flat‐panel displays and solid‐state lighting due to their steadily improved efficiency, tunable colors, narrow emission peak, and easy solution‐processing capability. However, because of high optical confinement and nonradiative charge recombination during electron–photon conversion, the highest reported efficiency of PeLEDs remains far behind that of their conventional counterparts, such as inorganic LEDs, organic LEDs, and quantum‐dot LEDs. Here a facile route is demonstrated by adopting bioinspired moth‐eye nanostructures at the front electrode/perovskite interface to enhance the outcoupling efficiency of waveguided light in PeLEDs. As a result, the maximum external quantum efficiency and current efficiency of the modified cesium lead bromide (CsPbBr3) green‐emitting PeLEDs are improved to 20.3% and 61.9 cd A?1, while retaining spectral and angular independence. Further reducing light loss in the substrate mode using a half‐ball lens, efficiencies of 28.2% and 88.7 cd A?1 are achieved, which represent the highest values reported to date for PeLEDs. These results represent a substantial step toward achieving practical applications of PeLEDs. 相似文献
12.
Degradation in organic light‐emitting diodes (OLEDs) is a complex problem. Depending upon the materials and the device architectures used, the degradation mechanism can be very different. In this Progress Report, using examples in both small molecule and polymer OLEDs, the different degradation mechanisms in two types of devices are examined. Some of the extrinsic and intrinsic degradation mechanisms in OLEDs are reviewed, and recent work on degradation studies of both small‐molecule and polymer OLEDs is presented. For small‐molecule OLEDs, the operational degradation of exemplary fluorescent devices is dominated by chemical transformations in the vicinity of the recombination zone. The accumulation of degradation products results in coupled phenomena of luminance‐efficiency loss and operating‐voltage rise. For polymer OLEDs, it is shown how the charge‐transport and injection properties affect the device lifetime. Further, it is shown how the charge balance is controlled by interlayers at the anode contact, and their effects on the device lifetime are discussed. 相似文献
13.
Sohee Jeon Lianfeng Zhao Young‐Jin Jung Ji Whan Kim Sei‐Yong Kim Hyeokjung Kang Jun‐Ho Jeong Barry P. Rand Jeong‐Hwan Lee 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(8)
Organic–inorganic hybrid perovskite light‐emitting diodes (PeLEDs) are promising for next‐generation optoelectronic devices due to their potential to achieve high color purity, efficiency, and brightness. Although the external quantum efficiency (EQE) of PeLEDs has recently surpassed 20%, various strategies are being pursued to increase EQE further and reduce the EQE gap compared to other LED technologies. A key point to further boost EQE of PeLEDs is linked to the high refractive index of the perovskite emissive layer, leading to optical losses of more than 70% of emitted photons. Here, it is demonstrated that a randomly distributed nanohole array with high‐index contrast can effectively enhance outcoupling efficiency in PeLEDs. Based on a comprehensive optical analysis on the perovskite thin film and outcoupling structure, it is confirmed that the nanohole array effectively distributes light into the substrate for improved outcoupling, allowing for 1.64 times higher light extraction. As a result, highly efficient red/near‐infrared PeLEDs with a peak EQE of 14.6% are demonstrated. 相似文献
14.
15.
16.
Light‐Emitting Diodes: Monolithic Flexible Vertical GaN Light‐Emitting Diodes for a Transparent Wireless Brain Optical Stimulator (Adv. Mater. 28/2018) 下载免费PDF全文
Han Eol Lee JeHyuk Choi Seung Hyun Lee Minju Jeong Jung Ho Shin Daniel J. Joe DoHyun Kim Chang Wan Kim Jung Hwan Park Jae Hee Lee Daesoo Kim Chan‐Soo Shin Keon Jae Lee 《Advanced materials (Deerfield Beach, Fla.)》2018,30(28)
17.
18.
19.