The Investigation Of Optoelectronic Properties Of Amorphous Graphite Like Carbon Nitride

Novel optoelectric materials, g-C₃N₄, with excellent semiconductor properties, medium bandgap as well as high thermal and chemical stabilities, has attracted a great deal of attention for its advanced potential applications in a vast range of fields, including optoelectronic, photocatalysis, optical sensor, bio-labeling and so forth. To further promote its practical applications, it is necessary to give an insight into its optoelectronic properties. However, up to now, there is still lack of understanding on its unique optoelectronic properties in general, which hampered its application to a great extent. Therefore, in this dissertation, we investigate the optoelectronic properties of g-C₃N₄ systematically via tuning it synthesis temperature, electronic state and morphology, which provides basic support for its further applications.By modulating the synthesis temperature, multicolor-emitting carbon nitride was successfully obtained. And the tunable photoluminescence mechanism of g-C₃N₄ was investigated via time-resolved emission spectra and Raman spectra and so forth. A novel schematic energy level diagram of g-C₃N₄ nanopowders is proposed base on the two dimensional π-conjugated polymeric network of carbon nitride and the lone pair of the carbon nitride.Furthermore, optoelectronic properties of g-C₃N₄ was modulated via doping with electronic-rich and electron-deficient elements. The doped products exhibits interesting relative photoluminescence with blue shifts, which are different from the traditional photoluminescence red shift caused by induced defect. To look insight into the variation of photoluminescence of g-C₃N₄, DFT calculation and time-resolved emission spectra were excuted. The changing of the electron density of π-conjugated polymeric network and LP state was thought to be responsible for the shift.In the end of this dissertation, we modulated the optoelectronic properties of g-C₃N₄ via tuning its morphology. Foam-like loosen structure g-C₃N₄ with large specific surface area was obtained via the assistance of bubble template. In addition, large aspect ratio g-C₃N₄ nanosheet was prepared via exfoliation by ultrasound with ―top-down‖ method, enabling the realization of materials dimensionality modulation form 3D to 2D. Herein, we investigated their optoelectronic properties in detail after morphology modulation. What is more, both of them exhibited enhancing photocatalytic performance in photo-degradation RhB experiment under sunlight.