ELECTRON-TRANSPORT IN VAPOR-DEPOSITED LAYERS OF 2-METHYL-2-PENTYL-1,3-BIS(DICYANOMETHYLENE)INDANE

Electron mobilities are measured in vapor-deposited amorphous layers of 2-melhyl-2-pentyl-1,3-bis(dicyanomethylene)indane, a highly polar acceptor compound with a dipole moment of 3.9 D. The results are described within the framework of a formalism based on disorder, due to Bassler and coworkers. The parameters of the formalism are sigma, the variance of the hopping site energies, mu(0), a prefactor mobility, and Sigma, the degree of positional disorder. Experimental values of sigma, mu(0), and Sigma. are 0.112 eV, 1.6 x 10(-3) cm(2)/Vs, and 1.6. The variance of site energies can be described by a model based on dipolar disorder. A comparison of the prefactor mobility with literature values for vapor-deposited acceptor glasses suggests that the prefactor is dependent on dipole moment, decreasing with increasing moment. The degree of positional disorder is similar to that observed in a wide range of vapor-deposited molecular glasses and attributed to packing constraints.