Enhancement of the non-photochemical hole-burning efficiency of a silicon naphthalocyanine in the presence of electron acceptor activators

We report on persistent spectral hole burning (PSHB) in a silicon-naphthalocyanine doped poly-vinylbutyral film in the presence of electron acceptors such as citral or hexachloroethane. The hole-burning efficiency does not depend on the concentration in 1-color PSHB experiments. The hole growth kinetics reflects the dispersion of the burning rates connected to the distribution of tunnel parameters of the two-level systems coupled to the electronic state of the dye. In 2-color experiments, an increase of the efficiency by a factor 10 compared with 1-color results with no acceptor is achieved with green gating light, the largest increase being observed with C70 as an acceptor.