Preparation and optoelectronic properties of a novel poly(N‐vinylcarbazole) with covalently bonded titanium dioxide

A functional organic–inorganic composite containing carbazole moieties (electron donors) and TiO2 (electron acceptors) in different molar ratios, TiO2‐modified poly(N‐vinylcarbazole) (PVK–TiO2), was synthesized through a nucleophilic reaction. The molecular and electronic structure of the PVK–TiO2 composite was characterized with Fourier transform infrared, ultraviolet–visible absorption, cyclic voltammetry, and so forth. The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the PVK–TiO2 composite were higher than those of pristine poly(N‐vinylcarbazole). The PVK–TiO2 composite exhibited an enhanced glass‐transition temperature and improved thermal stability. The photoinduced charge transfer observed in photofluorescence and photoconductivity measurements makes applications in the field of photodetectors possible. The PVK–TiO2 composite containing carbazole moieties and TiO2 in a molar ratio of about 58 :1 was found to have the best photosensitivity.