Preparation And Optoelectronic Properties Of The Films Of Inorganic Semiconductors-sensitized TiO₂ NanorodArrays

semiconductor is widely used in the field of photoelectricity because of its good chemical stability, long life of photoexcited electron, non-toxcity and pollution-free. Compared with TiO₂ nanoparticles, TiO₂ with one dimensional structures, for example, nanowire, nanotube, nanobelt, and so on, can offer a direct path for photoexcited electrons and enhance photoelectric performance. TiO₂ nanorod arrays attract a wide spread attention because of simple synthesis and low cost. However, the wide band gap of TiO₂ （3.0-3.2 eV） limits its absorption to ultraviolet light region. Various methods have been made to extend its absorption to visible light region, including the doping and deposition of metal and nonmetal elements, sensitization of dye or inorganic semiconductors with narrow band gaps and energetically high-lying conduction bands. So far, semiconductors with a narrow band gap, such as metal sulfide, carbon quantum dots, perovskite, metal halide oxide and so on, are studied extensively. "These semiconductors are applied to sensitize or co-sensitize TiO₂ to enhance its absorption of sunlight and photoelectric performance. In this thesis, we use Ag2S, Bi2S3, carbon quantum dots （CQDs）, BiOI, PbCrO4 to sensitize TiO₂ nanorod arrays （TiO₂ NRAs）, the main works and achievements are as follows:In the second chapter, we used hydrothermal method and successive ionic layer adsorption and reaction method （SILAR） to prepare TiO₂ NRAs and Bi2S3/Ag2S/TiO₂ thin films. We also explored the effects of the SILAR times of Bi2S3 and deposition sequence of Ag2S and Bi2S3 on the optoelectronic performance of Bi2S3/Ag2S/TiO₂ thin films. The results show that Bi2S3（3）/Ag2S（4）/TiO₂ thin film has enhanced absorption of sunlight, highest photocurrent and reduced resistance between the film and electrolyte. The short circuit current density is 0.456 mA/cm2, which is 10.3 times higher than that of single TiO₂ NRAs.In the third chapter, we used impregnation method and SILAR to prepare CQDs/TiO₂ and Bi2S3/CQDs/TiO₂ thin films. We also explored the influence of the SOLAR times of Bi2S3 on the optoelectronic performance of Bi2S3/CQDs/TiO₂ thin films. The results show that Bi2S3（3）/CQDs/TiO₂ thin film has enhanced absorption of sunlight, highest photocurrent and reduced resistance between the film and electrolyte. The short circuit current density is 0.309 mA/cm2, which is 7 times higher than that of angle TiO₂ NRAs.In the fourth chapter, we used SILAR method to prepare BiOI/TiO₂ and PbCrO4/TiO₂ thin films. We also explored the effects of the SILAR times of BiOI and PbCrO4 on the optoelectronic performance of BiOI/TiO₂ and PbCrO4/TiO₂ thin films. The results indicate that BiOI（8）/TiO₂ and PbCrO4（8）/TiO₂ thin films have highest photocurrent, photovoltage and reduced charge transfre resistance between the films and electrolyte. The short circuit current densities are 3 and 2.8 times higher than that of single TiO₂ NRAs, respectively.