Sundarapura Panus, Zhang Xiao-Mei, Yogai Ryoji, Murakami Kazuki, Fave Alain, Ihara Manabu
Department of Chemical Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8552, Japan.
Department of Mechanical Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8552, Japan.
Nanomaterials (Basel). 2021 Feb 11;11(2):459. doi: 10.3390/nano11020459.
The photovoltaic effect in the anodic formation of silicon dioxide (SiO) on porous silicon (PS) surfaces was investigated toward developing a potential passivation technique to achieve high efficiency nanostructured Si solar cells. The PS layers were prepared by electrochemical anodization in hydrofluoric acid (HF) containing electrolyte. An anodic SiO layer was formed on the PS surface via a bottom-up anodization mechanism in HCl/HO solution at room temperature. The thickness of the oxide layer for surface passivation was precisely controlled by adjusting the anodizing current density and the passivation time, for optimal oxidation on the PS layer while maintaining its original nanostructure. HRTEM characterization of the microstructure of the PS layer confirms an atomic lattice matching at the PS/Si interface. The dependence of photovoltaic performance, series resistance, and shunt resistance on passivation time was examined. Due to sufficient passivation on the PS surface, a sample with anodization duration of 30 s achieved the best conversion efficiency of 10.7%. The external quantum efficiency (EQE) and internal quantum efficiency (IQE) indicate a significant decrease in reflectivity due to the PS anti-reflection property and indicate superior performance due to SiO surface passivation. In conclusion, the surface of PS solar cells could be successfully passivated by electrochemical anodization.
为了开发一种潜在的钝化技术以实现高效纳米结构硅太阳能电池，研究了多孔硅（PS）表面二氧化硅（SiO）阳极形成过程中的光伏效应。PS层通过在含氢氟酸（HF）的电解液中进行电化学阳极氧化制备。在室温下，通过HCl/H₂O溶液中的自下而上阳极氧化机制在PS表面形成阳极SiO层。通过调节阳极氧化电流密度和钝化时间，精确控制用于表面钝化的氧化层厚度，以在保持PS层原始纳米结构的同时实现其最佳氧化。PS层微观结构的高分辨率透射电子显微镜（HRTEM）表征证实了PS/Si界面处的原子晶格匹配。研究了光伏性能、串联电阻和并联电阻对钝化时间的依赖性。由于PS表面的充分钝化，阳极氧化持续时间为30 s的样品实现了10.7%的最佳转换效率。外部量子效率（EQE）和内部量子效率（IQE）表明，由于PS的抗反射特性，反射率显著降低，并且由于SiO表面钝化而表现出优异性能。总之，通过电化学阳极氧化可以成功钝化PS太阳能电池的表面。
