Temperature dependence of the hopping mobility in amorphous tetracene

Time‐dependent photocurrent transients are measured with vapour deposited amorphous tetracene layers as a function of temperature employing the technique of sensitized hole injection from a selenium layer. The time dependence is exponential and reflects trapping. The trap‐free mobility, derived from the t = 0 current amplitude, obeys a μ ( T ) = μ ∞ exp [— ( T 0 / T ) 2 ] law with μ ∞ ≈ 0.4 to 0.8 cm 2 /Vs as predicted by previous Monte Carlo computer simulations for hopping across a Gaussian distribution of hopping sites in the long‐time limit. The Gaussian width, σ, given by T 0 , is of the order 0.1 eV, its dependence on sample formation temperature T F is in quantitative agreement with spectroscopic as well as TSC work, indicating that lattice relaxation around a localized charge carrier is irrelevant for carrier transport and σ is of purely electronic origin. A comparison is made with photoelectrons‐pectroscopic works.