New Methodology of Organic Electrochemical Synthesis - Fundamentals and Applications of Organic Electrochemistry - page 301

OPVC generates electric energy through the
charge separation state obtained by
photo-excitation, whereas electric energy
causes electron injection and hole injection, and
the subsequent charge recombination results in
emission in the OEL process.
To induce a charge separation state,
electron-donating and electron-accepting layers
are necessary in the thin film of the OPVC
( Figure 7.3 ). When the photo-excited state
(exciton) is generated in the donor layer by
solar energy at the near interface of the donor
layer and the acceptor layer, the excited
electron may migrate spontaneously to the
LUMO of the acceptor layer, resulting in the
formation of a charge-separated state. The
charge carriers then migrate by hopping
through each layer to the electrode terminals
and this process drives the photovoltaic cell.
Figure 7.3 Photo-electronic conversion
process