Charge-separation energy in films of p-conjugated organic molecules
نویسندگان
چکیده
Ž . Ž . We use inverse photoelectron spectroscopy IPES and ultraviolet photoelectron spectroscopy UPS to investigate Ž . unoccupied and occupied electronic states of five organic semiconductor materials: CuPc copper phthalocyanine , PTCDA Ž . Ž . Ž X X Ž . X 3,4,9,10-perylenetetracarboxylic dianhydride , a-6T a-sexithiophene , a-NPD N,N -diphenyl-N,N -bis l-naphthyl -l,l XX . Ž Ž . . biphenyl-4,4 diamine , and Alq tris 8-hydroxy-quinoline aluminum . The transport gap, E , is the difference between the 3 t highest occupied and lowest unoccupied molecular orbitals, measured via UPS and IPES. The charge separation energy, or exciton binding energy, is the difference between E and the optical gap, E , measured via absorption. E -E in these t opt t opt correlated materials ranges from 0.4 to1.4 eV. q 2000 Published by Elsevier Science B.V.
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