ELECTRON-TRANSPORT IN 2-T-BUTYL-9,10-N,N'-DICYANOANTHRAQUINONEDIIMINE

Electron mobilities are measured in vapor deposited layers of 2-t-butyl-9,10-N,N'-dicyanoanthraquinonediimine (DCAQ). The results are described within the framework of a formalism based on disorder, due to Bassler and coworkers. According to the formalism, charge transport occurs by hopping through a manifold of localized states with superimposed positional disorder. The key parameters of the formalism are sigma, the energy width of the hopping site manifold and SIGMA, a parameter that describes the degree of positional disorder. For DCAQ, sigma = 0.101 eV and SIGMA = 2.0. The experimental results are interpreted to show that the energy width of the hopping site manifold is mainly determined by dipole moments associated with the cyanoimine functionalities of the DCAQ molecule while the degree of positional disorder is attributed to packing constraints. A comparison is made between DCAQ and literature results recently reported for hole transport in a number of vapor deposited donor compounds.