Hide/Show Apps

Conjugation effects on carrier mobilities of polythiophenes probed by time-resolved terahertz spectroscopy

Esentürk, Okan
Kline, R. Joseph
Deongchamp, Dean M.
Heilweil, Edwin J.
Optically generated carrier conductivity of thiophene-based spin-cast polymer films, as cast poly(3-hexylthiophene) (P3HT) and both as cast and above liquid crystalline temperature annealed poly(2,5-bis(3tetradecylthiophen-2yl)thieno[3,2-b]thiophene) (PBTTT), were measured by time-resolved THz spectroscopy (TRTS) and compared to reported thin-film transistor (TFT) device measurements. The relative mobilities of the samples measured by TRTS agree well with reported TFl` mobilities. Since TRTS is sensitive to shortrange carrier mobility, this study suggests that increased mobility of PBTTT relative to P3HT films arises from improved ordering of the local structure, increased effective conjugation length, and planarity of PBTTT molecules in the solid state.