Light absorption by a layered structure of silicon particles as applied to the solar cells: Theoretical study

- Multilayer of silicon particles can absorb more light than the equivalent plate.
- Integral absorption coefficient of layered structure of silicon particles reaches 0.9.
- Growing the large particles leads to growing the absorption coefficient.
- The size of silicon particles should be close to the diffusion length order.
- Design of solar cell based on particulate system of silicon particles is proposed.

Absorption of a layered system (multilayer) consisting of monolayers of monodisperse crystalline silicon (c-Si) spherical particles is studied using the transfer matrix method. The wavelength range from 0.28 µm to 1.1 µm and the particle size range from 1 µm to 1000 µm are considered. The results for the particulate multilayer are compared with the ones for a homogeneous plane-parallel plate of the equivalent amount of silicon (equivalent plate). It is shown that at strong absorption of silicon the absorption coefficient of the plate is larger than the one of a single monolayer of particles. In the spectral range of small and middle absorption index of silicon absorption coefficient of the monolayer can exceed the one of the plate. Absorption coefficient of the system consisting of three and more monolayers exceeds the one of the equivalent plate. The integrated over the solar spectral irradiance (“Global tilt” ASTM G173-03) absorption coefficient is calculated. It is shown that the integral absorption of the particulate structure consisting of three and more monolayers of silicon particles is more than the one of the equivalent plate. Integral absorption coefficient of the four-monolayer system composed of particles with diameter of 1 µm is approximately 1.7 times larger than the one of the plate. It increases with the particles size and the number of monolayers increasing. The maximum value is close to 0.9. The scheme of the possible design of solar cell based on the particulate structure of active layer is proposed. The described method can be applied for light absorption optimization in solar cells based on silicon and other materials.