COMPUTER-SIMULATIONS OF LIGHT-SCATTERING AND ABSORPTION IN DYE-SENSITIZED SOLAR-CELLS

The TiO2 electrode of dye-sensitized solar cells (DSC) consists of 10- 30 rim sized particles which are sintered together. The effective surf ace of the TiO2 electrode is increased up to 1000 fold by the nanoporo us structure. It is covered with a layer of dye, so an acceptable over all absorption can be achieved. The absorption in the cell, and theref ore the current, can be further enhanced by light scattering in the el ectrode. However, as larger particles are needed for effective light s cattering, there will be the simultaneous effect of a decreasing effec tive surface. Computer simulations will be presented which show how th e absorption can be increased by optimizing the size of the TiO2 parti cles. Starting from Mie theory applied to coated spheres, multiple sca ttering is calculated using a numerical solution of the radiative tran sfer equation. Certainly, the particles are sintered together and the assumption of independent scattering is not valid, but the qualitative results should still remain valid. These calculations predict that a suitable mixture of small particles, which result in a large effective surface, and of larger particles, which are effective light scatterer s, have the potential to enhance solar absorption significantly. Furth ermore, electrodes made of multiple TiO2 layers are investigated, each layer consisting of particles of different sizes. (C) 1998 Elsevier S cience B.V. All rights reserved.