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The origin of the excited states and the spectroscopic features of polar molecular films and crystals of N,N-dimethylaminobenzylidene 1,3-indandione (DMABI) was considered. The formation of charge transfer exciton states in the absorption and luminescence spectra by increase of the thicknesses of DMABI films was observed. The evidence of a strong exciton-phonon interaction and its effects on the exciton absorption and luminescence spectra was discovered. The coexistence of free and self-trapped excitons at elevated temperatures was found in DMABI films. The dynamics of both shallow short-lived and deeply trapped long-lived self-trapped exciton states in various films and crystal of DMABI was discussed.derivatives. The CT can be responsible for excellent photoconducting properties of DMABI crystals and films.5'8 24 SPIE Vol. 2968 • 0277-786X/971$1 0.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/12/2015 Terms of Use: http://spiedl.org/terms

Hyperfine range (HFR) magnetic field ( H < 300 Oe) induced increase of photoconductivity and decrease of dark conductivity are observed in thin-layer sandwich type Autetrathiotetracene-A1 systems. The experimental results are interpreted in terms of HFR magnetic field influence on single-triplet transition rate of charge transfer (CT) states a t metal (Me)-organic semiconductor (0s) interface in the framework of Merrifield's et al.hyperfine interaction model. It is suggested that in the case of photoconductivity, triplet 3CT states are initially formed by molecular triplet exciton dissociation a t the Me-OS interface, whereas in the case of dark conductivity, singlet lCT states are initially formed in the process of non-equilibrium hole injection from the Me electrode. The HFR magnetic field reduces the lCT-3CT transition rate and is thus assumed to cause the observed increase of photo-and decrease of dark conductivity. The possible role of the inhomogeneous local magnetic field caused by the charge carriers trapped near the Me-OS interface on the rate of lCT"CT transition is also briefly discussed.