We report on physical mechanisms behind the temperature-dependent optical absorption, photoluminescence (PL), and photoconductivity in spin-coated films of a functionalized anthradithiophene (ADT) derivative, ADT-TES-F, and its composites with C 60 and another ADT derivative, ADT-TIPS-CN. Measurements of absorption and PL spectra, PL lifetimes, and transient photocurrent were performed at temperatures between 98 K and 300 K as a function of applied electric field. In pristine ADT-TES-F films, absorptive and emissive species were identified to be disordered H-aggregates whose properties are affected by static and dynamic disorder. The exciton bandwidths were ≤0.06 eV and ~0.115 eV for absorptive and emissive aggregates, respectively, indicative of higher disorder in the emissive species. The exciton in the latter was found to be delocalized over ~4-5 molecules. The PL properties were significantly modified upon adding a guest molecule to the ADT-TES-F host. In ADT-TES-F/C 60 composites, the PL was 2 considerably quenched due to photoinduced electron transfer from ADT-TES-F to C 60 , while in ADT-TES-F/ADT-TIPS-CN blends, the PL was dominated by emission from an exciplex formed between ADT-TES-F and ADT-TIPS-CN molecules. In all materials, PL quantum yield dramatically decreased as the temperature increased due to thermally activated nonradiative recombination. Considerable electric-field-induced PL quenching was observed at low temperatures at electric fields above ~10 5 V/cm due to tunneling into dark states. No significant contribution of ADT-TES-F emissive exciton dissociation to transient photocurrent was observed.In all materials, charge carriers were photogenerated at sub-500 ps time scales, limited by the laser pulse width, with temperature-and electric field-independent photogeneration efficiency. In ADT-TES-F/C 60 (2%) composites, the photogeneration efficiency was a factor of 2-3 higher than that in pristine ADT-TES-F films. In ADT-TES-F/ADT-TIPS-CN (2%) blends, an additional charge carrier photogeneration component was observed at room temperature at time scales of ~20 ns due to exciplex dissociation. At ~0.5-5 ns after photoexcitation, the carriers propagated via thermally-and electric field-activated hopping with an activation energy of ~0.025 eV. At time scales longer than ~5 ns, charge transport of carriers that are not frozen in traps proceeded through tunneling via isoenergetic sites.3