Environmental effects on temperature-dependent carrier transports in poly(3-hexylthiophene) films

Applications of poly(3-hexylthiophene) (P3HT) to solar cells have been reported. The reliability of organic solar cells is a key factor of full-scale applications in commercial optoelectronics. In this study, the environmental effect on the carrier transport in P3HT is researched. Charge-trapping phenomena are studied through time-domain measurement for P3HT thin-film transistors. The time-domain data confirm the hole-trapping model, indicating that water vapor influences the response by producing additional hole traps that serve to increase the current time constant. To understand the P3HT degradation mechanisms, an analysis through the temperature-dependent transfer characteristics is presented. It is shown that the hopping conduction behavior can be affected by exposure to ambient humidity and ambient atmosphere, inducing fluctuations in the hopping distance and the barrier height for hopping that serve to influence the carrier mobility.