The microstructures and optical and photoelectric conversion properties of spherical silicon (Si) solar cells were investigated and discussed. The surface of the spherical Si with a pn junction provided high crystallinity, and the lattice constant of the center of Si spheres is larger than that of the surface, which would be due to the lattice distortion by defect structures at the center of Si. The conversion efficiencies of spherical Si solar cells coated with SnO x :F anti-reflection thin films were improved by annealing. The optical absorption and fluorescence of the solar cells increased, and the lattice constants of SnO x :F anti-reflection layers decreased after annealing. The mechanisms of chemical reactions at the Si/metal interface were also discussed.

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Structure and properties of anti-reflection thin films of spherical silicon solar cells were investigated and discussed. Conversion efficiencies of spherical Si solar cells coated with F-doped SnO₂ anti-reflection films were improved by annealing. Optical absorption and fluorescence of the solar cells increased after annealing. Lattice constants of F-doped SnO₂ anti-reflection layers, which were investigated by X-ray diffraction, decreased after annealing. A mechanism of atomic diffusion of F in SnO₂ was discussed. The present work indicated a guideline for spherical silicon solar cells with higher efficiencies.

Structure and properties of spherical silicon solar cells with anti‐reflection thin films were investigated and discussed. Conversion efficiencies of spherical Si solar cells coated with F‐doped SnO2 anti‐reflection films were improved by annealing. Optical absorption and fluorescence of the solar cells increased after annealing. Lattice constants of F‐doped SnO2 anti‐reflection layers, which were investigated by X‐ray diffraction, decreased after annealing. Mechanisms of atomic diffusion in SnO2 and reactions at the Si/metal interface were discussed. The present work indicated a guideline for spherical silicon solar cells with higher efficiencies. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)