Photogeneration of free charge carriers in the donor–acceptor complex TBPDA·(C60)2

Abstract

The effect of a weak magnetic field with B₀ < 10000 G on the photoconductivity of the layered donor–acceptor complex TBPDA·(C₆₀)₂ has been studied. The Reaction Yield Detected Magnetic Resonance (RYDMR) spectrum provides evidence of a spin nature of the mechanism of free charge carrier generation in magnetic fields. A model of triplet–triplet annihilation of charge transfer excitons has been suggested. The model interprets the effect of a weak magnetic field on photoconductivity in TBPDA·(C₆₀)₂. The photoconductivity spectrum of the complex shows two peaks at 470 and 700 nm. The comparison of this spectrum with the optical absorption one indicates that both intermolecular charge transfer between neighboring C₆₀ molecules and direct charge transfer from the TBPDA to the C₆₀ molecules contribute to free charge carrier generation in TBPDA·(C₆₀)₂.