Acoustically improved performance in poly(3-hexylthiophene) based organic field effect transistor

Demonstration of acoustically improving charge transport characteristics of regioregular poly(3-hexylthiophene) (rrP3HT) based organic field effect transistor (OFET) fabricated on YZ lithium niobate piezoelectric substrate has been presented and analyzed. Owing to the acoustoelectric (AE) effect, a surface acoustic wave (SAW) propagating through the substrate transfers its momentum and energy to the charges in the rrP3HT channel, reducing the effective energy gap between the charge hopping states, which leads to a decrease in charge trapping and an increase in path conductivity and number of paths for charge transport. Hence, a significant increase in drain current and mobility and a substantial reduction in gate voltage were observed in the presence of SAW. The AE effect has been especially predominant in devices with smaller channel width, depicting that gate voltage brought down by 30 V provided drain current equivalent to that obtained in the absence of SAW. The bias stress analysis of the devices showed an increase in current instead of the decrease, generally seen with respect to time, reinforcing that the long term charge trapping effect in OFETs can be compensated with the propagation of SAW leading to enhanced device stability.

Automated summary

This study demonstrates and analyzes the acoustically improving charge transport characteristics of a regioregular poly(3-hexylthiophene) (rrP3HT) based organic field effect transistor (OFET) fabricated on a YZ lithium niobate piezoelectric substrate. The acoustoelectric (AE) effect leads to a reduction in the effective energy gap between charge hopping states, resulting in a decrease in charge trapping, an increase in path conductivity, and the number of paths for charge transport. The presence of a surface acoustic wave (SAW) significantly increases the drain current and mobility, and reduces the gate voltage. The bias stress analysis confirms that the propagation of SAW enhances the long-term stability of the OFETs by compensating for the charge trapping effect.