Charge transfer in complexes of C-60 and C-70 in solutions and solid state

Electronic absorption spectra of complexes of C-60 and C-70 fullerenes with donors, tetrathiafulvalene and pyranylidene derivatives, were studied in s olutions and in the solid state. Charge transfer bands were found in the 68 0-1300 nm range. The charge transfer energies (hv(ct)) for the C-60 and C-7 0 complexes, in solutions are close and almost independent of the solvent p olarity. For the C-60 complexes in the solid state, the dependence of hv(ct ) on the ionization potential (IP) of donors was found to be hv(ct) = 0.82I P - 3.93 eV. In the C-60 complexes in the solid state, the hv(ct) values ar e 0.15-0.20 eV lower than those in the solution. The linear dependences of hv(ct) on IP of donors for the C-60 complexes lie 0.6-0.7 eV higher than th ose in the complexes with tetracyanoethylene (TCNE). This is associated wit h lower values of the electron affinity of C-60 and the energy of the elect rostatic interaction in the fullerene complexes as compared to those of the TCNE complexes.