We have investigated the dependency of power conversion efficiency on deposition rate, substrate temperature, and post annealing during fabricating pentacene-based PIN photovoltaic cells with a structure of ITO/poly (3,4-ethylenedioxythiophene)poly (styrene sulfonate)(PEDOT: PSS)/pentacene/pentacene: C-60/C-60/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/Al. The maximum power conversion efficiency of pentacene-based photovoltaic cells has been achieved to be 2.25% by adjusting process parameters such as deposition rate (0.2 angstrom/s), substrate temperature (60 degrees C), and post annealing (200 degrees C). The effects of these parameters are elucidated from the device performance characteristics such as open-circuit-voltage (V-oc), short-circuit-current (J(sc)), and fill factor (FF).