Function File: osc_demo_daspk_exp_absorption ()

demo for the OSC simulator.

The device is a 1um long vertical BHJ, the light absorption coefficient is 1/1e-7 m.

The other model and parameters are those of Fig. 6(a) in the paper: "I.Hwang and N.Greenham. Modeling photocurrent transients in organic solar cells. Nanotechnology, 19:424012 (8pp), 2008".