Effect of interfacial shallow traps on polaron transport at the surface of organic semiconductors

The photo-induced electron and hole transfer across the semiconductor-dielectric interface in trap-dominated p-type organic field-effect transistors has been investigated. It has been observed that the transfer of electrons into the dielectric results in a decrease of the field-effect mobility of polarons, suggesting that additional shallow traps are generated in the conduction channel. Using this effect, the dependence of the field-effect mobility on the density of shallow traps, mu(N), has been measured, which allowed us to estimate the average polaron trapping time, tau(tr)=50 +/- 10 ps, and the density of shallow traps, N-0=(3 +/- 0.5)x10(11) cm(-2), in the channel of single-crystal tetracene devices.