碳纳米纤维"骨架"支撑的三维异质结硅太阳电池：设计和制备

3D thin film solar cells employing nanostructures as the supporting skeleton exhibit excellent light management and effective carrier collection like in radial pn junction nanowire arrays. Moreover, they have advantages including low materials usage, high compatibility with the present manufacturing of commercialized thin film solar cells, as compared to nanowire array-based ones. Thus 3D thin film solar cells are expected to have higher ratios of performance to cost and commercialization values. However, as the related research is still at the starting stage, it is lack of reports on preparation of high performance devices especially based on the theoretical understanding and optimization of the optical and electrical processes in the structures. In this project, we are going to systematically investigate and optimize the related optical and electrical processes, and then fabricate 3D heterojunction amorphous silicon thin film solar cells on carbon nanofiber arrays. Relative to the reported skeletons such as glass nanocones, ZnO nanorods and silver needles, carbon nanofibers combine the merits of good conductivity, high strength and tenacity, environmental friendliness, and abundant raw materials etc. Hydrogenated amorphous silicon carbide employed as the window layer has a wide bandgap,thus benefiting for improving the open circuit voltage and reducing the ineffective light absorption, which does not generate collectable carriers, as met in homojunction solar cells. Accordingly, some breakthroughs are worth expecting in experimental realization of related 3D thin film solar cells with high performance-to-cost ratios by implementing this project, thus providing valuable exploration for the industrialization.

纳米结构"骨架"支撑的三维薄膜太阳电池，除了具有类似于"径向pn结纳米线阵列"高效的光管理和载流子收集性能外，其材料的使用量更低且制备工艺与目前商用薄膜电池的相兼容。因此，具有更高的潜在性价比和商业化价值。然而，由于目前相关研究尚处于肇始阶段，缺乏结合光、电学过程的理论研究和优化的高效器件的制备工作。本项目将在我们对相关器件中光、电学过程理论研究的基础上，以碳纳米纤维阵列为"骨架"，制备结构和电、光学参数优化的三维异质结非晶硅薄膜太阳电池（该结构亦可推广至晶化硅等薄膜电池）。与目前报道的"骨架"材料（如纳米玻璃锥、氧化锌纳米棒、纳米银针等）相比，碳纤维兼具良好的导电性、高的强度和韧性、环境友好、原材料丰富等优点。另外，利用氢化非晶硅碳作窗口层可以提高电池的开路电压并减少对入射光的无效吸收。因此，本研究有望在高性价比三维硅薄膜电池的实验实现上有所突破，为其产业化提供有益的探索。

随着化石能源使用引起的环境污染及温室气体效应的加剧，新能源的开发变得迫在眉睫。光伏发电作为一种重要的清洁能源利用方式，受到广泛的关注。由于目前光伏组件主要是基于晶体硅材料，相对成本偏高，阻碍了其民用化普及。通过研发新的太阳电池材料、结构、工作机制等，从而提高相关器件的性价比是该领域的研究热点。本研究从减少材料使用（成本），提高器件性能两方面入手，开展了以碳纳米纤维作支撑结构的三维异质结硅太阳电池的理论设计和原型器件初步实现的研究工作。取得了以下主要的研究进展和结果：（i）通过系统的理论模拟，建立了纳米/亚微米（波长）半导体结构与太阳光的互作用模型，为具有高性能光管理半导体纳米结构的开发提供了一般性的指导原则；（ii）在上述原则指导下，制备了光电转换效率分别为4.3%和5.8%的三维氢化非晶硅和结晶硅薄膜原型器件；（iii）在上述工作的基础上，首次实现了利用热化学气相沉积技术生长结构可控的直立石墨烯结构。上述研究成果将为相关高性能器件的开发奠定一定了理论和实验基础，提供一定的有价值的参考。