Optimization of active layer thickness for high performance organic tandem solar cells by combining the optical and the charge transport models

Recently, the tandem architecture has received a great attention as a strategy for achieving high efficient organic solar cell. In order to fully exploit the opportunity offered by this tandem approach, the thicknesses of the front and the back cells must be carefully optimized. In this study, to model the operation of tandem organic solar cells, we combined the optical model for the light absorption and the drift-diffusion equations for the charge-transport. The thicknesses of each sub-cells of tandem solar cell, based on poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b'] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] as donor material for front cell and poly(3-hexylthiophene) as donor material for back cell and methanofullerene as acceptor material for both sub-cells, are optimized for high power conversion efficiency. Dependency of performance parameters of tandem organic solar cell on the thickness of active layers is investigated by using this combined model.