Photoinduced valence instability in the organic molecular compound tetrathiafulvalene-<i>p</i>-chloranil (TTF-CA)

Abstract

It was found that a local charge-transfer excitation on the donor(D)-acceptor(A) pair leads to a semimacroscopic valence change from the quasi-ionic (${\mathit{D}}^{+}$${\mathit{A}}^{\mathrm{\ensuremath{-}}}$) to quasineutral (${\mathit{D}}^{0}$${\mathit{A}}^{0}$) states in organic molecular-compound TTF-chloranil with mixed DA stacks. Photogenerated neutral-ionic domain walls, which are responsible for anomalous photoconductivity, show the temporal annihilation due to the one-dimensional recombination.