Constructions And Performances Of Tio₂Nanostructure Based Hybrid Thin Film Solar Cells

The environmental pollution is aggravating and traditional non-renewable energy is constantlydepleting with the development of world economy. Much attention has been paid to the development ofsolar energy due to its advantages such as rich, sustainable and environment friendly. Organic-inorganichybrid and all solid state solar cells with thin films have become a research hotspot in the field of solar cellsat present. TiO2is environment friendly, abundant in storage, relatively stable for acid-base and has beenwidely used as absorbing material and window layer of solar cell. In this paper, we detailed the in-situhydrothermal synthesis of TiO2on the FTO transparent conductive glasses and the influencing factors. Aseries of organic-inorganic (TiO2/P3HT, TiO2/MEH-PPV) hybrid thin film solar cells based on TiO2wereassembled and the preparation technology, basal effect, solvent effect and surface modification ofTiO2/P3HT or TiO2/MEH–PPV were also studied. The main results of our research work are summarizedas follows:(1) TiO2thin films with nanostructure were in situ synthesized in different solvents and thephotoelectric performances were also studied respectively. TiO2thin film was synthesized in one step on theFTO substrate, in which tetrabutyl titanate was choosed as precursor, concentrated hydrochloric acid anddeionized water (or ethylene glycol, polyethylene glycol (peg)400, xylene, etc.) were used as solvent. Thefilm that consists of the uniform distribution of nanorods is of homogeneous density. We discussed theinfluences of different experimental conditions on the membrane, explored the growth mechanism andphotoelectric properties of TiO2thin film, assembled the device with the structure ofFTO/TiO2/MEH-PPV/Ag and obtained the photoelectric conversion efficiency of0.160%. The preparedfilm is thin in thickness and has a good contact with the substrate, besides no other additives such assurfactant were added to the solution. Ultimately we got some nanorods which have small sizes, wideoptical band gaps and good absorptions in the uv area.(2) TiO2thin films with nanostructures were synthesized by two steps and the photoelectricperformance was also studied. First a layer of metal titanium was sputtered on the surface of the FTOconductive using Magnetron sputtering apparatus and then calcined, then it was used in solvothermal reaction and at last the TiO2thin film with homogeneous permutation nanorods was formed. The preparedfilm is uniform and compact, the crystallinity is very good without calcination, and the film has a goodcontact with the substrate and doesn’t crack. TiOx can serve as a barrier to prevent short circuit when theelectrode is evaporated on the film, and the method of preparing seed layer is simple and easy to operate,what`s more, the thickness of seed layer is controllable. The hybrid thin film solar cells with devicestructure of FTO/TiO2/P3HT/Ag were assembled and the performance parameters of optimal device wereobtained: an open-circuit voltage of0.231V, a short circuit of0.38mA/cm2, a fill factor of40.08%, andenergy conversion efficiency of0.034%.(3) The preparation of TiO2:CuO hybrid membrane and photoelectric performance of the device werestudied in this thesis. TiO2thin film is in situ synthesized on the FTO substrate using solvent hot methodand then the TiO2thin film is soaked in salt solution with different concentrations, later the film is calcinedto form TiO2:CuO composite film. This method is simple and easy to operate, and the experimental processis environmentally friendly. CuO belongs to the p-type semiconductor and has absorption in the visible partdue to its optical band gap of1.0~1.9eV, so it can be used to modify the surface of TiO2thin film toimprove the utilization of sunlight, so as to improve the photoelectric conversion efficiency of the device.Finally the hybrid thin film solar cells with the device structure of FTO/TiO2:CuO/MEH-PPV/Ag wereassembled, and the performance parameters of the optimal device were obtained: an open-circuit voltage of0.581V, a short circuit of0.349mA/cm2, a fill factor of41.77%, and energy conversion efficiency of0.076%.