面向热光伏的表面等离激元增强可见-红外光谱转换调控研究

Exploring renewable energy including solar energy provides one of the solutions to the energy crisis and enviromental pollution. Solar thermophotovoltaic technology can break the Shockley-Queisser limit in conversion efficiency and thus shows more appealing prospect with respect to conventional photovoltaic technology. However, in current thermophotovoltaic technology, the conversion efficiency is considerably low. To alleviate this issue, a visible-to-infrared spectrum conversion in structured metals based on surface plasmon polaritons is proposed. The visible light transfers into heat through wide-angle broadband absorption and then the heated emitter radiates narrowband and directional infrared light. Therefore, the conversion efficiency is significantly enhanced. Besides, layered structures integrating absorption layer, thermal transport layer and radiation layer are enabled to miniaturize the device significantly. This project focuses at the visible-to-infrared spectrum coversion and solves two key scientific issues: how to realize efficient absorption of visible light through field enhancement and how to realize coherent thermal radiation of infrared light through field transformation. The physics behind the absorption of visible light, heat transfer and infrared coherent radiation will be investigated. The related integrated device will be designed, fabricated and characterized. The results will provide new ideas not only for developing energy-efficient nano-devices aiming at advanced thermophotovoltaic technology, but also befinite several related disciplinaries including nanophotonics, energy science and material sciences.

新能源是解决能源危机和环境污染的基本途径之一。热光伏相比传统光伏技术，转换效率可以突破Shockley-Queisser极限，具有更广阔应用前景。针对目前热光伏技术中可见-红外光谱转换效率低现状，项目提出基于微纳金属表面等离激元的新型光谱转换技术。该方案创新在于：最大限度在同一低热阻金属集成单元层减小热阻失配，引入突破衍射限制微纳金属结构减小热输运距离，两者结合提升热定向输运效率；利用表面等离激元调控光热和热光能量转换，从而提高光谱转换效率。项目围绕高光谱转换效率这一目标，针对微纳米光场增强光吸收、温度场调控热定向输运、微纳米光场变换红外热辐射三个关键科学问题，研究微纳金属可见-红外光谱转换过程能量转换和输运的物理机理和调控机制，设计、制备和表征相应的集成功能器件。项目的研究成果对于发展面向热光伏的绿色微纳光电子技术和学科综合交叉性（微纳光学、新能源科学、新材料科学等）具有重要意义。

本项目基于微纳金属表面等离激元实现光吸收和红外热辐射，并展示其红外应用。项目在高能效器件研究方面取得进展，在国际光学领域刊物上共发表SCI论文10篇，包括Light Science and Applications2篇，Laser and Photonics Review3篇，Physical Review Letters1篇。项目培养博士生3人，硕士生2人。项目取得代表性研究成果包括：（1）针对金属光热吸收波长和带宽限制，实现多款带宽可重构高效超薄光热吸收器件，包括超宽带(400-1700nm,带宽覆盖可见和近红外波段)高效(84%)光热器件，（2）针对红外热辐射调谐难题，率先将微纳结构与相变材料结合，实现对热辐射率和辐射波长的精确调控，实现对热辐射率大动态范围(0.2-0.97)连续调控, 热辐射强度增加远高于斯特藩-玻尔兹曼定律热辐射,（3）基于红外热辐射率动态调控，首次展示适应背景温度变化的红外伪装技术，当背景温度30-50度变化时，目标红外热辐射率相应改变从而保持伪装状态，同时该技术能在0-60度宽视场角范围保持良好伪装效果。项目的研究成果对于发展绿色微纳光电子技术和学科综合交叉性（微纳光学、新能源科学、新材料科学等）具有重要意义。