Semiconductors group

Abstract:

We have investigated the charge photogeneration dynamics at the interface formed between single-walled carbon nanotubes (SWNTs) and poly(3-hexylthiophene) (P3HT) using a combination of femtosecond spectroscopic techniques. We demonstrate that photoexcitation of P3HT forming a single molecular layer around a SWNT leads to an ultrafast (∼430 fs) charge transfer between the materials. The addition of excess P3HT leads to long-term charge separation in which free polarons remain separated at room temperature. Our results suggest that SWNT-P3HT blends incorporating only small fractions (1%) of SWNTs allow photon-to-charge conversion with efficiencies comparable to those for conventional (60:40) P3HT-fullerene blends, provided that small-diameter tubes are individually embedded in the P3HT matrix.

Abstract:

We have used terahertz spectroscopy to measure the conductivity and time-resolved photoconductivity of a range of semiconducting nanostructures. This article focuses on our recent terahertz conductivity studies on semiconductor nanowires and single walled carbon nanotubes. © 2010 IEEE.

Abstract:

An understanding of aggregation effects in organic semiconductors is essential for their effective use in optoelectronic devices. Typically, the electronic dynamics in such systems are heavily dependant upon the aggregation state, and dynamics often occur on sub-nanosecond timescales. © 2010 IEEE.