Photoelectric Properties of Titanium Dioxide/Graphene Quantum Dots Semiconductor Material and its Computer Simulation

Abstract

As an excellent inorganic semi-conductor material, titanium dioxide (TiO2) is widely applied in some photo-induced hardware designs. The energy gap with 3.0 eV to 3.2 eV enables TiO2 to respond only to the incident light of ultraviolet band, while TiO2 can’t effectively utilize visible light. Therefore, TiO2 needs to be modified to reduce the overall energy gap. Graphene quantum dots (GQDs) is adopted to modify TiO2 and further made into photoelectrode hardware devices. In this case, the energy gap of GQDs is measured by cyclic voltammetry, and it reaches only 1.18 eV. GQDs can directly absorb visible light photons and then transform them into electrons. After that, electrons are transmitted into TiO2 conduction band (CB) to form photocurrents. In the experiment, computers are utilized in simulation to change reaction conditions. The photoelectric properties of the materials adopted to prepare GQDs-TiO2 devices are different. Compared with single anatase or rutile type TiO2, mixed crystal TiO2 possesses better photoelectric property as photo-anode material. In the prepared semi-conductor device (GQDs-TiO2), the nitrogen content in the composition of GQDs is increased to further enhance the photoelectric property of devices. The change of the wavelength of incident light shows that the photons between 430 nm and 476 nm wavebands and in the wavebands above 526 nm can effectively enhance photocurrents. The introduction of GQDs reduces the energy gap of prepared photoelectric devices and enabled the prepared devices to respond to high-wavelength photons. GQDs-TiO2 photoelectrode devices with 3 times nitrogen content show the best photoelectric enhancement effects at 750 °C.