Aggregate formation and its effect on (opto)electronic properties of guest-host organic semiconductors

摘要

We quantify guest molecule aggregation and its effect on the photoconductive properties of guest-host thin films, depending on the guest concentration and host material. A high-performance anthradithiophene (ADT) derivative served as a guest, while functionalized benzothiophene (BTBTB) and polymethylmethacrylate (PMMA) were chosen as hosts. Aggregates exhibited redshifted optical absorption and photoluminescence (PL) spectra, as well as reduced PL quantum yields. Propensity toward guest aggregation differed for PMMA and BTBTB hosts. Photocurrents dramatically increased as the percentage of aggregated guest molecules increased due to considerably higher charge carrier mobility in the aggregates. At low guest concentrations, BTBTB films outperformed PMMA films.