Figure 4. Effect of gate bias on OFET sensitivity.

Sensitivity (defined as photocurrent per unity incident light intensity) as a function of photon energy at the flat-band voltage (solid black curve; purely photoconductive response) and V_g=0 (dashed red curve); 3.1 eV photon energy. The higher sensitivity in the latter case is a result of a combined contribution from the photoconductive and the photovoltaic effects. The contribution from the photovoltaic effect also increases the steepness of the dependence of the photocurrent on photogeneration rate (compare data shown by red solid circles and black open squares in the inset).