The electronic energy bands of charge transfer complexes α-MTDTPY. TCNQ(1), β-MTDTPY.TCNQ(2) and MTDTPY.CHL(3) were calculated by tight binding EHMO. In 1, the electron donor, molecule MTDTPY, and the electron acceptor, molecule TCNQ, form a quasi one-dimensional mixed molecular column with alternative packing, and there is no net intercolumn charge transfer. The energy gap E=0.15eV. The charge carriers are created by thermo-exciting from band E~H~O to E~L~U. As for 2 and 3, the electron donor, molecule MTDTPY and electron acceptor, molecules TCNQ and CHL appear in relatively separated quasi one-dimensional molecular columns respectively. Charge carriers mainly come from inter-column charge transfer. Based on the calculated structure of energy bands and according to the equation of the migration of charge carriers of Frohlich-Sewell, the proportion of the room temperature electrical conductivities for these crystals is σ1:σ2:σ3=3.75×10^-^1^0:1:1.15, and it is fundamentaly coincide with the relevant experimental results. In 2, the ratio of contributions of molecular column MTDTPY (D) and TCNQ (A) to electrical conductivity is σD:σA=10^3:1, and for 3, the corresponding ratio of MTDTPY (D) and CHL (A) is σD:σA=2:1. Besides, the migration mechanisms of charge carriers of these crystals have been discussed.

Key words: CRYSTALS, CHARGE TRANSFER COMPLEX, CHARGE TRANSFER, CHARGE EARRIER (CARRIER), ELECTRICAL CONDUCTIVITY, MIGRATION MECHANISM