Av. Vannikov et al., RELATION BETWEEN ELECTROLUMINESCENCE AND ELECTRON-TRANSPORT CHARACTERISTICS OF SUBSTITUTED POLY(PHENYLENEVINYLENE)S, High energy chemistry, 30(2), 1996, pp. 115-119
The influence of conditions of electrode coating with a polymer film a
nd features of carrier transport through the polymer layer on the char
acteristics of photo- and electroluminescence was considered for poly(
1,4-phenylene-1-phenylvinylene) (MP-PPV), oly[1,4-phenylene-1,2-di(4-m
ethoxyphenyl)vinylene] (DMOP-PPV), and oly[1,4-phenylene-1,2-di(4-phen
oxyphenyl)vinylene] (DPOP-PPV). It was found that electroluminescence
efficiency increases by more than two orders of magnitude in going fro
m MP-PPV and DMOP-PPV to DPOP-PPV. This difference is associated with
the fact that mobile charge carriers in DPOP-PPV are of both signs and
radiative charge recombination occurs in the bulk of the polymer. In
the case of MP-PPV or DMOP-PPV, this process occurs at the cathode, wh
ere electrons injected into the polymer are localized and the radiativ
e recombination competes with the direct discharge of the holes at the
cathode. It was shown that the quantum efficiency of electroluminesce
nce is an order of magnitude higher for vacuum-deposited polymer layer
s than for films spin-cast from solution.