Direct observation of the carbazole hole trap in polymer solid films by the charge-resonance band

The carbazole (Cz) hole trap was directly observed at 77 K in the copolymer of N-vinylcarbazole (VCz) with methyl methacrylate (the mole fraction of VCz < 50%) by the measurement of the charge-resonance band. It is found that the Cz hole trap in solid films is mainly stabilized by charge resonance between two Cz chromophores and that the fraction of more stable Cz hole traps increases with Cz concentration.