Tsuchime-like cost-efficient aluminum film to enhance absorption in thin and ultra-thin photovoltaic cells

Silicon solar cells account for more than ninety percent of the photovoltaic (PV) market, primarily due to convenience, cost-effectiveness, and long service life. However, the light absorption efficiency of PV cells remains a limiting factor, especially for thin and ultra-thin solar panels. Most methods for increasing light absorption in thin and ultra-thin solar cells are either cost-ineffective or technically challenging, given the thinness of the functional layers employed. In this article, we propose employing a lithography-free and cost-efficient approach to increase the light absorption in thin and ultra-thin solar cells using a Tsuchime-like self-forming nanocrater (T-NC) aluminum (Al) film. T-NC Al film can be obtained by the well-known process of electrochemical anodizing of Al followed by etching the nanoporous alumina (Al2O3). According to the current study, T-NC film boosts the average absorbance in the 400-1100 nm wavelength range by 85.9, 64.3, 46.3 and 41.8% for PV cells with silicon active layer thickness of 500 nm, 1 µm, 3 µm, and 10 µm, respectively. Moreover, the wavelength range of increased absorption depends on silicon thickness, where the peak of absolute increase of absorbance moves from 620 nm to 950 nm as the thickness of the silicon layer increases from 500 nm to 10 µm. Therefore, T-NC Al film allows for a significant increase in the efficiency of thin and ultra-thin solar cells without involving costly top-down techniques such as lithography.