The Reflection Spectra of the Crystalline Electron Donor-Acceptor Complexes of TCNQ

Abstract

Abstract The polarized reflection spectra were measured on the crystals of TCNQ complexes with phenothiazine, anthracene, pyrene, acenaphthene, carbazole, hexamethylbenzene, and 1,10-phenanthroline. The crystalline absorption spectra were obtained by the K-K transformation of the reflection spectra. The charge-transfer degree and the stabilization energy in the ground state were estimated for each complex by analysing the charge-transfer bands in the solid state. The charge-transfer degree of the TCNQ–phenothiazine complex is 19.6%, while those of the TCNQ–carbazole, anthracene, and hexamethylbenzene complexes are 12.0, 10.5, and 8.0% respectively. Furthermore, those values for TCNQ–1,10-phenanthroline, acenaphthene, and pyrene are about 5%. The relationship between the charge-transfer excitation energy and the ionization potential of a series of the donor molecules is also discussed.