晶硅薄膜的低温外延生长、纳米光子学陷光和基于剥离技术的柔性太阳电池研究

Ultra-thin crystalline silicon solar cell with low cost and high efficiency is the direction of the PV industry in the near future. The objective of this project is to enable the development of heterojunction and hybrid solar cells based on crystalline silicon thin film from the combination of low temperature epitaxial growth of silicon, advanced light-trapping from the field of nanophotonics and low temperature stress-induced exfoliation technology. High quality epitaxial silicon thin film will be prepared using PECVD or HWCVD at a temperature lower than 400°C based on the investigation of the epitaxial growth and defect mechanisms. Optimized nano-texture and solar cell structure will be proposed based on the computer simulations. Based on the studies of the interface passivation and carrier recombination, high optical absorption and high electrical collection will be realized at the same time. Investigate the thermal stress-induced exfoliation technology of epitaxial film and then determine the low cost process of the flexible solar cells. The aim of this project is to achieve an efficiency of ~17% for heterojunction or hybrid solar cells based on crystalline silicon thin film with an absorption layer thickness <10um. Techniques suitable for large scale will be proposed. The successful of this project will promote the flexible application of Si solar cell and the healthy and sustainable development of PV industry.

低成本高效晶硅薄膜电池是未来光伏产业发展方向。本项目把低温外延和纳米光子学陷光结合起来，结合低温剥离工艺，制备基于晶硅薄膜的异质结和有机-无机复合的柔性太阳电池。通过研究PECVD和HWCVD低温外延晶硅薄膜的生长和缺陷产生机理，在不超过400度下制备高质量外延膜；通过对光吸收和电输运特性的数值模拟和实验研究，确定优化的纳米光子学陷光结构和电池器件结构；在有效钝化界面、揭示载流子输运复合机理的基础上，同时实现高光吸收和高电收集；研究外延膜的热应力剥离技术，确定低成本、柔性晶硅薄膜电池的工艺流程。在吸收层厚度不超过10微米下，获得转换效率~17%的晶硅薄膜电池；提出适合大规模推广的技术路线。通过该项目实施所取得的成果可拓展硅电池的应用空间，有效推动光伏产业的健康可持续发展。

系统研究了热丝化学气相沉积技术外延硅薄膜的工艺技术和薄膜成核生长过程，获得了高质量的外延硅薄膜。采用环氧树脂固化剥离技术初步实现了外延硅薄膜的成功剥离。实现了适合超薄晶硅的表面陷光结构的可控制备技术。对适合超薄柔性晶硅的、工艺温度低于200度的、低工艺成本的多种新型硅异质结太阳电池工艺进行了研究，开发了热丝氧化升华法和全溶液法等适合柔性超薄晶硅电池制备工艺，探索了多条基于氧化物和有机半导体载流子传输层的柔性晶硅电池制备技术路线。实现基于全溶液法低温工艺的有机/无机复合柔性晶硅薄膜太阳电池效率大于17.3%。为有效拓展硅基电池的应用空间奠定了基础。