Bipolar Charge Transport in Poly(3-hexyl thiophene)/Methanofullerene Blends: A Ratio Dependent Study

TL;DR

This study examines how the ratio of donor to acceptor materials in P3HT:PCBM blends affects bipolar charge transport, revealing high mobilities and complex transient behaviors across various compositions.

Contribution

It provides a detailed analysis of charge mobility and transient behaviors in P3HT:PCBM blends as a function of composition, highlighting bipolar transport phenomena.

Findings

Bipolar charge transport observed across all blend ratios.

High charge mobilities of 10^(-3) - 10^(-2) cm^2/Vs at 90% PCBM.

Multiple transit times and double transients in specific ratios.

Abstract

We investigated the charge carrier mobility in pristine poly(3-hexyl thiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) blend devices by applying the time resolved photoconductivity experiment in dependence on the donor:acceptor ratio. We observe a bipolar transport in all studied samples ranging from pure polymer to polymer:fullerene with 90% PCBM content. For the ratios P3HT:PCBM 1:4 and 1:1 we observe two transit times in the electron current transients, as well as hole double transients for P3HT:PCBM 1:2. We find high hole and electron mobilities in the order of 10^(-3) - 10^(-2) cm^2/Vs for a concentration of 90% PCBM in the blend.