硅/PEDOT:PSS核壳纳米线太阳能电池中势垒高度对光伏性能的影响及其物理机制研究

Recently, Si/conducting polymer（PEDOT:PSS） core/shell nanowire solar cells have brought much attention because of their low cost and high efficiency in principle. However, the nanostructured device exhibits low power conversion efficiency, which is primarily limited by the recombination of photogenerated charge carriers..In this project, we attempt to minimize the recombination of photogenerated charge carriers by increasing the barrier height of the Si/PEDOT:PSS core/shell nanowire Schottky junction. Specifically，the Schottky barrier height will be modified by adjusting the work function of PEDOT:PSS through doping and so on. The relations between the device perfoamance and the barrier height will be investigated. In addition, the effects of the barrier height on the recombination of photogenerated charge carriers will be understood by measuring the internal quantum efficiency， and the underlying physical mechanisms assocaited with the device performance midified by the barrier height will be clarified. Finally, low-purity Si/PEDOT:PSS core/shell nanowire solar cells will be prepared, and the obtained law and machanisms can guide us to tune the work function of PEDOT:PSS, thus decreasing or eliminating the effects of the purity of Si on the device photovoltaic performance..This project will provides a scientific background and a technical solution for lowering the recombination of photogenerated charge carriers in the low-purity Si/conducting polymer (PEDOT:PSS) core/shell nanowire solar cells and optimizing the device performance.

硅/导电聚合物(PEDOT:PSS)核壳纳米线太阳能电池原理上可实现低成本、高效率，成为当前光伏研究领域中的热点之一。本项目的前期工作结果表明:导致原理型器件效率偏低的主要原因是光生载流子复合。本项目拟通过增大硅/PEDOT:PS核壳纳米线肖特基结的势垒高度来降低光生载流子复合。具体实施, 采用掺杂等方式调整PEDOT: PSS功函数,实现对肖特基结势垒高度的调控，探究势垒高度对器件光伏性能影响的规律。通过内量子效率测试与分析，理解势垒高度对光生载流子复合的影响,揭示势垒高度调控光伏性能的潜在物理机制。在此基础上,制备低纯硅/PEDOT:PSS核壳纳米线太阳能电池,基于获得的规律与机制来调整PEDOT:PSS功函数,降低或消除硅原料纯度对器件光伏性能的影响。通过本研究，为解决硅/PEDOT:PSS核壳纳米线光伏电池中光生载流子复合问题及优化低纯硅器件的性能提供科学依据和技术支持。

硅/导电聚合物(PEDOT:PSS)核壳纳米线太阳能电池原理上可实现低成本、高效率，成为当前光伏研究领域中的热点之一。器件效率偏低的主要原因是光生载流子界面相关的复合，需要探究其解决方法及研究相关科学规律。本项目主要探究了可控制备硅/ PEDOT:PSS核壳纳米线阵列及调控纳米结构的硅/ PEDOT:PSS肖特基结的势垒高度，进一步研究势垒高度对器件光伏性能影响的规律和机制。主要研究内容和结果如下：. (1)采用金属援助硅化学刻蚀法制备器件级面积的硅纳米线阵列和硅纳米孔阵列，获得了硅纳米结构的可控制备方法。通过掺杂偶极高分子PFI实现了PEDOT:PSS功函数有效调控，PEDOT:PSS导电聚合物的功函数随着PFI溶液掺入比的增加而增大，最大提升了约0.6eV。. (2)获得了溶液填充和气相聚合两种制备硅/导电聚合物核壳纳米线阵列的可靠方法，实验结果说明硅/导电聚合物核壳纳米线阵列结构有利于高效光捕获、光生电荷分离和收集及广角光伏转换，同时实验证实硅/导电聚合物核壳纳米线阵列是一种光电化学制氢可供选择的电极材料及结构. (3)通过掺杂偶极高分子到PEDOT:PSS中能够有效地提升硅/PEDOT:PSS核壳纳米线阵列肖特基结势垒高度，该势垒高度的提升能够使器件暗电流减小了3-4个数量级，相应的光伏电池的开路电压随势垒高度的提升而增加，其物理机制起源于势垒高度提升降低了光生载流子热发射的间接复合。. (4)探究了以低纯度物理法冶金晶硅位初始原料制备核壳纳米线阵列结构光伏电池，实验证实了核壳纳米线阵列结构的光诱捕和短的光生载流子分离路径的优势能够战胜其几何结构诱导的光生载流子复合，能够降低晶硅纯度对电池光伏性能的影响。. 通过本研究，为解决硅/PEDOT:PSS核壳纳米线光伏电池中光生载流子复合问题及优化低纯硅器件的性能提供科学依据和技术支持。