Photoionization-induced charge separation for efficient solar energy conversion

The most important primary process in solar energy conversion systems is photo-induced charge separation. This Perspective summarizes our current understanding of the photoionization-induced charge separation process, which involves the transfer of an electron from a discrete to a continuous electronic state with particular emphasis on the threshold energy and efficiency of photoionization. Based on our understanding of alkane solutions and in aromatic organic crystals, the charge separation mechanism in dye-sensitized solar cells is discussed as a photoionization-induced solar energy conversion system.