Chemical diffusion coefficient in dye sensitized solar cells as a function of porosity and surface roughness

Abstract

In this work we introduce equations describing the morphological dependency of electron transport in nano-structured solar cells. Using the hopping model for electron transport and using the trap contained diffusion model we define an expression to explain the dependency of the electron diffusion coefficient and conductance versus porosity and surface roughness. Validity of the obtained theoretical formula is examined by a random walk simulation based on hopping model in a fully disordered medium with a random distribution of energy. A Monte-Carlo random walk simulation was used to investigate the effects of morphology on the electron transport in the porous nano-structures. For generation of the random packing of nanoparticles, a stochastic cluster model was utilized. The porosity and surface roughness of the generated porous media were tuned by changing the particle size and the overlap parameters.