Polaron Motional Narrowing of Electron Spin Resonance in Organic Field-Effect Transistors

Polaron states in organic thin-film transistors (TFTs) were investigated by the electron spin resonance (ESR) technique. Gate-field-dependent and temperature-dependent single-Lorentzian ESR spectra were observed for field-induced polarons in pentacene TFTs, demonstrating the effect of motional narrowing due to polaron diffusion. Analyses of the ESR linewidth revealed a considerably long trapping time (tau_(C) approximately 0.7 ns), the variation of which is discussed in terms of the multiple trap-and-release model.