Optical, electrochemical and electrical properties of p-N,N-dimethyl-amino-benzylidene-malononitrile thin films

A donor-acceptor small organic molecule, p-N,N-dimethyl-amino-benzylidene-malononitrile (DABMN), has been synthesized and successfully prepared in thin films using spin coating technique. The thin film of DABMN exhibited semiconductor behavior with an optical band gap of about 2.27 eV. The photoluminescence spectrum was exhibited a strong red emission. The energy levels of lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) were determined by experimental calculation from cyclic voltammetry. The electrical performance of the ITO/DABMN/Al structure device was evaluated through current-voltage characteristics and showed a typical Schottky diode behavior with good charge mobility. The charge density associated with the DABMN film was calculated from the capacitance-voltage measurements. (paper)