The active region can be formed of a variety of light absorbing materials such as crystalline silicon (c-Silicon), amorphous silicon (??-silicon), cadmium telluride (CdTe), copper indium diselenide (CIS), copper indium gallium diselenide (CIGS), light absorbing dyes and polymers, polymers having light absorbing nanoparticles disposed therein, III-V semiconductors such as GaAs etc.