Understanding effects of TCO work function on the performance of organic solar cells by numerical simulation

The influences of work function of transparent conducting oxides (TCO) on the per-formance of organic solar cells, including open circuit voltage, conversion efficiency and fill factor, has been simulated. It is obtained that for non-Ohmic contact the open circuit voltage and conversion efficiency increase monotonically with the TCO work function but keep constant for Ohmic contact. Fill factor decreases and increases with the electrode work function when the electrode work function is below and above a critical value (4.2 eV for TCO and 4.5 eV for back-contact), respectively. The results of this simulation are significant in the choice of TCO contacts to optimize organic planar heterojunction solar cells.