Autoionization of Excitons in Organic Solar Cells

Abstract

It has been shown that in addition to the conventional mechanism of photovoltaic effect in organic solar cells (OSCs), which is the ionization of molecular excitons on impurities, a new mechanism is possible in nanoscale cells, namely, tunneling autoionization in a strong electric field of the pn junction. Its quantum yield for molecular excitons and charge-transfer excitons becomes higher than for ionization on impurities with a cell length of less than 20–25 or 60–80 lattice periods (~10 and ~25 nm), respectively. The possibility of creating cascades of series-connected OSCs with a quantum yield close to 1 on the basis of the new mechanism is discussed.