钙钛矿/硅异质结叠层太阳电池中关键功能材料与器件实现的基础研究

The project is aiming to further improve the conversion efficiency of the existing solar cells by an efficient monolithic combination of a perovskite solar cell as the top cell and a silicon heterojunction (SHJ) solar cell as the bottom cell. The perovskite solar cell is a potential candidate for new generation low-cost and high-efficiency solar cell product. The optimum bandgap of the perovskite absorbing layer in the top cell will be optimized by theoretical simulation and realized by controlling its composition. Through a distinctive structural design and implementation of the carrier transport layer, low temperature deposited transparent electrode, and tunneling junction, the fabrication process of the perovskite/SHJ tandem solar cell will be established. The major innovations are the introduction of a reactive plasma deposition (RPD) technique with low ion bombardment to prepare the conductive electrode with a high transparency in a wide spectrum and a high conductivity to improve the performance of the perovskite top cell; and the adoption of an inorganic n-type nanocrystalline-SiOx:H (n-nc-SiOx:H) material assembled with the p-nc-SiOx:H emitter junction to form tunnel junction with a low photovoltaic loss. Because the n-nc-SiOx:H has the advantages of high conductivity and high transparency, the open-circuit voltage (Voc) is therefore largely improved. The working principle of the perovskite/SHJ monolithic integration will be clarified to further improve the performance of the tandem cell. Therefore, this project would have a significant practical application value; and it would establish the technology foundation for the research of semitransparent and flexible perovskite solar cells; and the design principle of novel high performance tandem solar cells with the perovskite top cell and other bottom solar cells such as Cu(In, Ga)Se2 (CIGS).

本项目旨在进一步提高现有电池效率，将具低成本、高效率潜力的钙钛矿电池与硅异质结电池相结合，构建高效钙钛矿/硅异质结两端叠层太阳电池。拟通过理论模拟给出钙钛矿顶电池吸收层所需最佳帯隙；并通过组分调节实现钙钛矿材料帯隙的可控制备；通过载流子传输层、低温透明电极以及隧穿结的独特结构设计及其实现，贯通两端叠层电池工艺。本项目的创新性在于：引入反应等离子沉积（RPD）技术实现低离子轰击、宽光谱高透过和高电导的透明电极的制备，以提升钙钛矿顶电池性能；采用无机N型纳米硅氧，利用其高电导和高透过的特性，与硅异质结底电池的p型纳米硅氧发射级形成低光电损失的隧穿结，进而大幅提升叠层电池开路电压；拟深入阐明钙钛矿/硅异质结两端叠层太阳电池的工作原理，进而提高叠层电池的性能。本项目的研究对促进钙钛矿电池与其它电池（如铜铟镓硒）构建新型高效叠层电池以及透明和柔性钙钛矿电池等的研究奠定了基础，具有重要的实用价值。

本项目的提出是为进一步提高现有电池效率，将具有低成本、高效率的钙钛矿电池与硅异质结电池相结合，构建高效钙钛矿/硅异质结两端叠层太阳电池。理论模拟了钙钛矿顶电池吸收层所需帯隙和厚度匹配方案；进行了SnO2电子传输层的研究，基于该电子传输层的钙钛矿太阳电池的效率达到17.38%；在此基础上进行了溶液方法的NiOx和CuSCN空穴传输层材料的研究，通过对空穴传输层材料的表面改性和制备工艺的调控获得了效率分别为17.1%和16.6% 的钙钛矿电池；另外，引入反应等离子体技术（RPD）进行了低温、低离子轰击、宽光谱高透过和高导电的透明导电薄膜的制备；同时进行了硅异质结底电池及基于纳米硅基薄膜的隧穿结的研究；为提高硅底电池近红外光响应并提高叠层电池中顶、底电池电流匹配和连接效果，从背部光管理、正面光管理两个方面展开了研究。使得平面硅异质结太阳电池转换效率达到了19.04%；最后，通过叠层电池中钙钛矿顶电池的带隙、厚度和陷光管理的研究，初步获得了开路电压超过1.8V，效率超过20%的钙钛矿/硅异质结两端叠层太阳电池。本项目的研究对加快钙钛矿电池与其它电池（如铜铟镓硒）构建新型高效叠层电池以及透明和柔性钙钛矿电池等的研究奠定了基础，具有重要的实用价值。