Fourier-transform infrared and optical absorption spectra of P-N,N-dimethylaminobenzylidenemalononitrile (DBM) thin films

Abstract

Thin films of P-N,N-dimethylaminobenzylidenemalononitrile (DBM) were prepared for the first time using thermal evaporation technique. The molecular structure and electronic transitions of DBM films were investigated by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), and ultraviolet–visible (UV–vis) spectra. The observed vibrational wavenumbers in FTIR spectra were analyzed and assigned to different normal modes of the molecule. UV–vis optical absorption spectral measurements of DBM films were analyzed to obtain the type of the optical transitions. The values of the optical gap ( E opt ), the transport gap ( E t ), the exciton binding energy ( E B ), the urbach's energy ( E u ), the dispersion parameters, the molar extinction coefficient ( ɛ mol), the oscillator strength ( f), and the electric dipole strength ( q 2) were also reported.