Thickness optimization of organic solar cells by optical transfer matrix

The thickness of organic solar cells (OSCs) has been optimized by simulating current-voltage (J-V) behavior. Because the thickness of active layer (several hundred nanometers) in OSCs is comparable with the illumination wavelength, optical transfer matrix is applied to rigorously determine the optical electric field in thin-film devices, which is strongly affected by the optical interference. The simulation results indicate that there exists an optimal thickness, depending on both carrier mobility and recombination loss. The performance of OSCs becomes worse with increasing thickness from this optimal value because of the aggravated recombination loss. Moreover, it is revealed that improving carrier mobility is an effective way to boost the value of optimal thickness and hence further optimize the performance of OSCs.