1. Charge transfer in organic semiconductors: from microscopic to macroscopic electronic properties on all time scales
Oksana Ostroverkhova, Oregon State University, Corvallis, OR 97331
Goals: to understand charge transport and trapping and to explore relationship between macroscopic conductivity and microscopic charge-transfer
Materials: functionalized pentacene (Pc-TIPS), anthradithiophene (ADT-TIPS-F) and dicyanomethylenedihydrofuran (DCDHF) derivatives. Films are drop-cast from toluene solution.
Methods: time-resolved conductivity and fluorescence, combined with fluorescence microscopy
Outcomes:
Photoconductivity:
Observed:
Fast charge generation and bandlike transport
Morphology- and structure- dependent picosecond time-scale charge trapping
Electric field-assisted detrapping
Light-induced trap filling
Fluorescence:
Identified fluorescent and non-fluorescent photoconductive derivatives to serve as single-molecule reporters of the charged state and photoconductive matrix, respectively
Observed fluorescence lifetime reduction in solid-state compared to solution
Observed fluorescence quenching upon oxidation
DCDHF
DCDHF+