SINGLET AND TRIPLET ENERGY-TRANSFER IN TETRACYANOBENZENE-BIPHENYL CRYSTALS

Singlet and triplet excitonic energy migration in mixed-stack charge-t ransfer crystals of tetracyanobenzene-biphenyl (TCNB-B) doped with ant hracene (10(-4)-10(-2) M/M) have been studied within temperature range 5-300 K by using optical, spectroscopic and kinetic techniques. It ha s been found, that the motion of excitons is thermally activated with the activation energies of 450 +/- 60 and 550 +/- 60 cm (-1) for the s inglet and triplet excitons, respectively. The later value differs fro m the activation energy in undoped TCNB-B crystals (where it is 360 +/ - 60 cm(-1)) and suggests that doping with anthracene perturbs the hos t crystal lattice.