Theoretical simulations of optical confinement in dye-sensitized nanocrystalline solar cells

The application of light scattering of submicron TiO2 particles to dye-sens itized nanocrystalline photoelectrochemical cells is examined theoretically . Monte Carlo simulations reveal that the increase of absorption path lengt h of photons in nanocrystalline films and optical confinement due to total reflections at solar cell surfaces improve light absorption in the sensitiz ed films remarkably. Contribution of optical confinement to the improvement is much greater than that of the increase of absorption path length. Quant um efficiencies are calculated, considering the recombination of electrons in the nanocrystalline films. The application of light scattering improves the quantum efficiencies remarkably, especially in long wavelength lights. Optical confinement permits utilization of thinner sensitized films. Distri butions of light absorption in the scattering films are also discussed. The distributions are not represented as exponential expressions due to light reflections in the vicinities of transparent conductive oxide (TCO) electro des. Optical confinement decreases the light reflections and improves light absorption next to the TCO electrodes where generated electrons can diffus e without recombinations. (C) 2000 Elsevier Science B.V. All rights reserve d.