Promoting Light Extraction Efficiency of Ultraviolet Light Emitting Diodes by Nanostructure Optimization
Biaomin Li,
Shihong Xia,
Wei Guo,
Zhenhai Yang,
Yuheng Zeng,
Zhizhong Yuan,
Jichun Ye
Affiliations
Biaomin Li
School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, China
Shihong Xia
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
Wei Guo
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
Zhenhai Yang
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
Yuheng Zeng
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
Zhizhong Yuan
School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, China
Jichun Ye
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences (CAS), Ningbo 315201, China
Ultraviolet (UV) light-emitting diodes (LEDs), as one of the more promising optoelectronic devices, are intrinsically limited by poor light extraction efficiencies (LEEs). To unlock the full potential of UV-LEDs, we propose a simple and effective strategy to promote the LEEs of UV-LEDs by screening and tailoring suitable optical structures/designs through rigorous numerical simulations. The photonic crystals (PCs) and/or nano-patterned sapphire substrates (NPSSs) equipped with the nano-pillar, nano-cone, nano-oval, and their derivates, are particularly investigated. The simulated results show that individual PC with an average transmittance of 28% is more efficient than that of individual NPSS (24.8%). By coupling PC and NPSS structures, a higher LEE with an average transmittance approaching 29% is obtained, much higher than that of the flat one (23.6%). The involved mechanisms are clarified and confirm that the promotion of optical performance of the nanostructured devices should be attributed to the widened response angles (from 0 to 60°), rather than the enhanced transmittances in the small angles within 30°.
