Zhang Huili, Lei Yakui, Zhu Qiang, Qing Tong, Zhang Ting, Tian Wanghao, Lange Matthias, Jiang Meiping, Han Chao, Li Jun, Koelle Dieter, Kleiner Reinhold, Xu Wei-Wei, Wang Yonglei, Yu Linwei, Wang Huabing, Wu Peiheng
Research Institute of Superconductor Electronics (RISE)/School of Electronics Science and Engineering , Nanjing University , Nanjing , 210023 , People's Republic of China.
National Laboratory of Solid State Microstructures/School of Electronics Science and Engineering/Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing , 210093 , People's Republic of China.
ACS Nano. 2019 Sep 24;13(9):10359-10365. doi: 10.1021/acsnano.9b04149. Epub 2019 Sep 5.
The actual light absorption photovoltaic responses realized in three-dimensional (3D) radial junction (RJ) units can be rather different from their planar counterparts and remain largely unexplored. We here adopt a laser excitation photoelectric microscope (LEPM) technology to probe the local light harvesting and photoelectric signals of 3D hydrogenated amorphous silicon (a-Si:H) RJ thin film solar cells constructed over a Si nanowire (SiNW) matrix, with a high spatial resolution of 600 nm thanks to the use of a high numerical aperture objective. The LEPM scan can help to resolve clearly the impacts of local structural damages, which are invisible to optical and SEM observations. More importantly, the high-resolution photoelectric mapping establishes a straightforward link between the local 3D geometry of RJ units and their light conversion performance. Surprisingly, it is found that the maximal photoelectric signals are usually recorded in the void locations among the standing SiNW RJs, instead of the overhead positions above the RJs. This phenomenon can be well explained and reproduced by finite element simulation analysis, which highlights unambiguously the dominant contribution of inter-RJ-unit scattering against direct mode incoupling in the 3D solar cell architecture. This LEPM mapping technology and the results help to achieve a straightforward and high-resolution evaluation of the local photovoltaic responses among the 3D RJ units, providing a solid basis for further structural optimization and performance improvement.
在三维（3D）径向结（RJ）单元中实现的实际光吸收光伏响应可能与其平面对应物有很大不同，并且在很大程度上仍未得到探索。我们在此采用激光激发光电显微镜（LEPM）技术，以探测构建在硅纳米线（SiNW）基质上的3D氢化非晶硅（a-Si:H）RJ薄膜太阳能电池的局部光捕获和光电信号，由于使用了高数值孔径物镜，其空间分辨率高达600 nm。LEPM扫描有助于清晰地分辨局部结构损伤的影响，而这些损伤在光学和扫描电子显微镜观察中是不可见的。更重要的是，高分辨率光电映射在RJ单元的局部3D几何结构与其光转换性能之间建立了直接联系。令人惊讶的是，发现最大光电信号通常记录在直立SiNW RJ之间的空隙位置，而不是RJ上方的顶部位置。这种现象可以通过有限元模拟分析得到很好的解释和再现，该分析明确突出了RJ单元间散射对3D太阳能电池架构中直接模式耦合的主导贡献。这种LEPM映射技术和结果有助于对3D RJ单元之间的局部光伏响应进行直接且高分辨率的评估，为进一步的结构优化和性能提升提供了坚实基础。
