Acoustically Assisted Charge Transport in Poly(3-hexylthiophene)

This work reports for the first time acoustoelectric charge transport in an organic semiconductor, regioregular poly(3-hexylthiophene), (rrP3HT) deposited as thin films on surface acoustic wave (SAW) devices generating shear horizontal and Rayleigh SAW. With the propagation of SAW, an enhancement in current was observed, especially when the applied bias field was in the direction of wave propagation. The momentum and energy transfer from SAW helped to reduce charge trapping at trap states and increase the free charge density, assisting the drift current. The mechanical and electrical effects of the acoustic wave were independently studied by using a non-piezoelectric substrate and by screening the mechanical deformations of SAW, respectively, in order to support the observations. The devices displayed high stability on repeated exposure of the SAW while they were monitored for 1 week under ambient conditions (temperature at around 24 °C and humidity at around 44% RH).