Ultra energy efficient III-nitride/polymer hybrid white LEDs using nanotechnology

采用纳米技术的超节能 III 族氮化物/聚合物混合白光 LED

• 批准号: EP/H004602/1
• 负责人: Tao Wang
• 金额: $ 49.63万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH004602%2F1
• 关键词: Ultra; energy; efficient; III; nitride

The last decade has seen dramatic advances in the development of III-nitride light emitters, whose emergence is significantly changing many aspects of our lives. Materials from the III-nitride family can emit light over the complete visible spectrum and a major part of the ultraviolet (UV) and are ideally suited for white light sources. Developments in solid-state lighting are occurring at pace and will lead to near-ultimate lighting sources, likely to be based on III-nitride materials. This will result in a fundamental change in the concept of illumination and has the potential to lead to massive savings in energy, estimated to be equivalent to $112 billion by the year 2020. Such increases in efficiency are increasingly important due to the growing world-wide energy-crisis and threat of global warming.Currently, there are three main approaches for the fabrication of white light emitting diodes (LEDs) needed for solid-state lighting: (1) a package of three LED chips each emitting at a different wavelength (red, green and blue, respectively); (2) a combination of a blue (460 nm) LED with a yellow phosphor pumped by blue light from the LED; (3) a single chip emitting UV light which is absorbed by three phosphors (red, green and blue) and reemitted as a broad spectrum of white light. The first method is ideal for achieving a true white light source, but it is extremely difficult to balance the electro-luminescence intensities of these different colours and there exist a number of fundamental challenges related to the different requirements of the individual LEDs. The performance of current UV-LEDs is far below blue-LEDs and presents a major limitation to the third route. As a result the blue LED+ phosphor approach is maintaining its strong lead for the fabrication of white LEDs with several commercial successes. However, the most promising commercially available white LEDs are based on blue epiwafers with the highest crystal quality, which are thus extremely expensive. This raises the price and thus limits their applications in general illumination. Further development of the technology is also still faced with problems, which are the driving force behind the new type of LED proposed here. We aim to develop a hybrid nanotechnology delivering a new type of ultra high energy efficient white-LED without need for the premium price blue epiwafers. The technologies to be hybridised are arrays of semiconductor nano-rods, with dimensions on the scale of 100s of nanometres, metal nano-particles and polymers. Building on our work demonstrating efficient light emission from conjugated polymers we will optimise these materials for converting blue light to yellow. The new polymers will be used to fill the spaces between nanorods prepared in GaN-based LED structures, maximising the contact between the blue light source and the yellow emitter. Blending silver nano-particles into the polymer will be used to further improve optical performance as a result of a coupling effect between the metal and semiconductor. Relatively thick capping layers usually limit the strength of this effect but the close contact between the polymer/metal blend and the side-walls of the nano-rods enables us to get close to the full benefit.This work will combine the existing strengths at the Sheffield in III-nitride device fabrication and characterisation of III-nitride emitters with those at Strathclyde in polymer chemistry, fundamental optical studies of III-nitrides and characterization of nanostructures, including metal nanoparticles and semiconductors. This combined effort aims to achieve an improved understanding of the fundamental issues in the optical emission processes mentioned above and to optimise fabrication processes of hybrid III-nitride/polymer white LEDs. It will lead to the demonstration of next generation white-LEDs suitable for replacement of conventional light sources in terms of cost and luminous efficacy.

在过去的十年里，III-氮化物发光二极管的发展取得了巨大的进步，它的出现正在显著地改变我们生活的许多方面。来自III-氮化物系列的材料可以在整个可见光光谱和大部分紫外线(UV)上发射光线，非常适合用作白色光源。固态照明的发展正在以PACE的速度进行，并将导致近乎最终的光源，很可能是基于III-氮化物材料。这将导致照明概念的根本变化，并有可能导致大量能源节约，预计到2020年将相当于112亿美元。由于日益严重的全球能源危机和全球变暖的威胁，这种效率的提高变得越来越重要。目前，制造固态照明所需的白色发光二极管(LED)的主要方法有三种：(1)由三个LED芯片组成的封装，每个芯片分别发射不同的波长(红、绿和蓝)；(2)将蓝色(460 Nm)LED与由LED的蓝光泵浦的黄色荧光粉组合；(3)发出紫外光的单晶片，可被三种荧光粉(红、绿、蓝)吸收，并以广谱白光的形式重新发射。第一种方法是实现真正的白色光源的理想方法，但要平衡这些不同颜色的电致发光强度是极其困难的，并且存在与不同LED的不同要求相关的许多基本挑战。目前的UV-LED的性能远远低于蓝光LED，这是第三种路线的主要限制。因此，蓝色LED+荧光粉方法在制造白色LED方面保持着强大的领先地位，并取得了几次商业成功。然而，最有前景的商用白色LED是基于晶体质量最高的蓝色外延片，因此价格极其昂贵。这提高了价格，从而限制了它们在一般照明中的应用。该技术的进一步发展也面临着一些问题，这些问题是本文提出的新型LED背后的驱动力。我们的目标是开发一种混合纳米技术，提供一种新型的超高能效白色LED，而不需要溢价的蓝色外延片。将被混合的技术是半导体纳米棒阵列，其尺寸为100纳米、金属纳米颗粒和聚合物。在我们展示共轭聚合物高效发光的工作的基础上，我们将优化这些材料，将蓝光转换为黄色。这种新型聚合物将被用来填补GaN基LED结构中制备的纳米棒之间的空隙，最大限度地增加蓝色光源和黄色发射器之间的接触。由于金属和半导体之间的耦合效应，将纳米银颗粒掺入聚合物中将被用于进一步改善光学性能。相对较厚的盖层通常会限制这种效应的强度，但聚合物/金属混合物与纳米棒侧壁之间的紧密接触使我们能够接近完全的好处。这项工作将结合谢菲尔德III-氮化物器件制造和III-氮化物发射器的表征与Strathclyde在聚合物化学、III-氮化物的基础光学研究以及纳米结构(包括金属纳米颗粒和半导体)表征方面的现有优势。这一联合努力旨在更好地了解上述光学发射过程中的基本问题，并优化混合III-氮化物/聚合物白光LED的制造工艺。这将导致在成本和发光效率方面适合取代传统光源的下一代白光LED的展示。

项目成果

Polarized white light from hybrid organic/III-nitrides grating structures.

• DOI: 10.1038/srep39677
• 发表时间: 2017-01-03
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Athanasiou M;Smith RM;Ghataora S;Wang T
• 通讯作者: Wang T

Greatly enhanced performance of InGaN/GaN nanorod light emitting diodes

• DOI: 10.1002/pssa.201100456
• 发表时间: 2012-03
• 期刊: physica status solidi (a)
• 作者: J. Bai;Q. Wang;T. Wang

Non-polar (11-20) GaN grown on sapphire with double overgrowth on micro-rod/stripe templates

• DOI: 10.1088/1361-6641/aaed93
• 发表时间: 2018-12-01
• 期刊: SEMICONDUCTOR SCIENCE AND TECHNOLOGY
• 影响因子: 1.9
• 作者: Bai, J.;Jiu, L.;Wang, T.
• 通讯作者: Wang, T.

Characterization of InGaN-based nanorod light emitting diodes with different indium compositions

• DOI: 10.1063/1.4725417
• 发表时间: 2012-06-01
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Bai, J.;Wang, Q.;Wang, T.
• 通讯作者: Wang, T.

Fabrication of two-dimensional InGaN/GaN photonic crystal structure using a modified nanosphere lithography technique

• DOI: 10.1063/1.4805035
• 发表时间: 2013-05-13
• 期刊: APPLIED PHYSICS LETTERS
• 影响因子: 4
• 作者: Athanasiou, M.;Kim, T. K.;Wang, T.
• 通讯作者: Wang, T.