Charge transport studies on novel PT-derivatives with hydrophilic anchoring groups

Abstract

Using charge extraction techniques we have clarified the charge transport properties of novel poly-thiophene derivatives intended for use as sensitizers in polymer sensitized solar cells. The polymers are of low molecular weight in order to enable penetration into a mesoporous titanium dioxide film. Hydrophilic anchoring units are attached to the thiophene ring to facilitate attachment of the polymer to the titanium dioxide. The hole transporting properties were determined in order to clarify the possibility of using the polymers both as sensitizers and hole transporting material in a hybrid type device. We found that the mobilities are in the range of 1-4•10-8 cm 2 /Vs. The low mobility is compensated by very long charge carrier lifetimes in the order of 100 ms resulting in a very promising charge carrier drift distance of 1 µm.

Charge transport in intercalated and non-intercalated polymer:fullerene blends

“…This can be understood from the MillerAbrahams hopping rate formalism which consists of a temperature dependent part, related to the energetic disorder, and a temperature independent part related to the rate of the longest jump (electronic coupling). It has been shown that weak electronic coupling can lead to very low mobilities even for materials with low activation energies and Gaussian widths [16]. For efficient charge transport low energetic disorder (small s) and strong electronic coupling (high m 1 ) is desired.…”