Study of organic photovoltaics by localized concentrated sunlight: Towards optimization of charge collection in large-area solar cells

Large-area organic solar cells are known to suffer from a major efficiency decrease which originates from the combination of a voltage drop across the front electrode and the voltage-dependent photocurrent. In this letter, we demonstrate this efficiency loss on large area, indium tin oxide free cells with a hexagonal current collecting front grid, by measurements of light intensity dependence of the cell performance. The results show a major difference in the cell performance measured under localized and uniform illuminations. Subsequently, we demonstrate ways in which the current collecting efficiency could be raised. (C) 2011 American Institute of Physics. [doi:10.1063/1.3656276]