大面积可控亚微米硅锥阵列黑硅太阳能电池基础研究

Black silicon has shown great potential in solar cell applications, whose absorption rate reaches 90 % or higher over the band from 0.25 to 2.5 μm, covering almost the full solar spectrum. In terms of fundamental research, how to maximize the photoelectric conversion efficiency depends on the accurate control and rational optimization of its structural parameters. Nevertheless, yet the dependence of photoelectric mechanism on the structural parameters cannot be investigated quantitatively owning to the fact that all the processing methodologies available so far has failed to produce the required regular and controlled microstructures. For practical applications, large scale and low cost processing technologies have not been developed either. This proposal aims at overcoming the present difficulties by introducing a new pattern transferring technology, which is a combination of 2D array assembly of colloidal microspheres and photoelectrochemical etching process. Black silicon with high aspect-ratio submicron structures can be processed on 3 inch wafer-scale area. Owning to the accurate control of silicon cone array at a submicron level, the scaling effect of photoelectric conversion mechanism in black silicon materials can be investigated quantitatively and the multi-objective optimization on its structural parameters may also be achieved. With the optimized microstructure, the fabrication of black silicon solar cell beyond the Shockley-Queisser limit can be expected hopefully. Furthermore, it is postulated that the waveguide effect of sub-micron silicon cone array can be used to enhance the photoelectric conversion process as a new mechanism based on the controlled microstructures. A detailed investigation on this new mechanism is significant for understanding of the interaction between photons and atoms in low dimensional structures, which remains an open fundamental problem in physics.

黑硅材料在0.25～2.5微米的几乎整个太阳光谱范围内具有90%以上的光吸收率，在太阳能电池领域具有重要应用前景。然而，在基础研究上，为实现高效的光电转换，依赖于对结构参数的优化和精确控制，而目前黑硅加工技术面临着结构不规则的瓶颈问题，导致无法对结构参数和光电转换机制的关系进行定量地实验研究；在应用研究上，则缺乏大面积、低成本的加工技术。本项目提出胶体微球二维阵列化和光电化学刻蚀相融合的图形转移技术，能加工三英寸以上大面积的高深宽比亚微米黑硅结构，对硅锥阵列结构参数的控制精度可提高到亚微米量级，从而能定量研究黑硅光电转换机制中的尺度效应，并解决其复杂结构特征中的多目标参数优化问题，有望突破Shockley-Queisser极限。基于该结构，本项目还提出研究亚微米硅锥光波导效应对光电转换的影响机制这一科学问题，对研究低维结构中光子与原子的相互作用这一基本物理问题具有重要意义。

黑硅材料在0.25～2.5微米的几乎整个太阳光谱范围内具有90%以上的光吸收率，在太阳能电池领域具有重要的应用前景。然而，在基础研究上，为实现高效的光电转换，依赖于对结构参数的优化和精确控制，黑硅加工的结构不规则，导致无法对结构参数和光电转换机制的关系进行定量的实验研究；在应用研究上，则缺乏大面积、低成本的加工技术。本项目利用胶体微球二维阵列化和光电化学刻蚀相融合的图形转移技术，能加工三英寸以上大面积的黑硅结构，实现了黑硅材料特征尺寸和阵列规则性在亚微米量级精度的控制，初步探索了黑硅材料减反和广谱吸收机制中尺度效应的可量化规律，解决了黑硅材料复杂结构中的多目标参数优化问题，建立了亚微米量级特征尺度高度规则的黑硅太阳能电池光电转效率的理论模型，制造实现了基于亚微米硅锥结构的黑硅太阳能电池器件原型，实现了项目研究目标，为突破实现高效硅基太阳能电池的低成本、大面积制造，实现一种新型的高度规则的黑硅结构太阳能电池及其加工技术奠定了基础。进一步的，本项目研究探索了亚微米量级光波导阵列结构的光电转换效率增强机制，进而对研究低维结构中光子与原子的相互作用这一基本物理问题具有重要意义。