Structure And Performance Investigation Of Quantum Dot Sensitized Solar Cells Based On Different Crystal TiO₂ Photoanodes

Energy crisis and environmental problems are one of the great challenges today.Solar cells have become a promising alternative energy source because of their green characteristics.In the third generation of solar cells,quantum dot sensitized solar cells（QDSSCs）are one of the hot topics in current research.As an important component of QDSSCs,the photoanode film is the carrier support of quantum dots（QDs）and an important medium of charge transfer.Due to the limitation of quantum dot load of photoanode film and its own photoelectric characteristics,the efficiency of the solar cell cannot be further improved.As a result,the progress of QDSSCs has been limited in recent years.In this thesis,low-cost and eco-friendly Ti O₂ was selected as raw material,the transparent Ti O₂photoanodes and laser-modified Ti O₂ photoanodes were prepared to improve the efficiency and application of QDSSCs.The research contents and results are as follows:1.A facile method was developed to prepare transparent Ti O₂ films.The Ti O₂ film was obtained by spin-coating of n-butyl titanate solution on the surface of fluorine-doped Sn O₂conductive glass（FTO）,which reacted with steam and was transferred to furnace for high temperature sintering.The film thickness can be controlled by the number of spin coating.The transmittance of a layer of Ti O₂ film prepared by this method is more than 90%in the visible light range,while keeping the effective absorption of ultraviolet light by Ti O₂.The assembled QDSSCs is with certain transparency.The optimal energy conversion efficiency（PCE）was 2.92%.2.The laser plasma ablation method was adopted to transform anatase and rutile Ti O₂into corresponding black Ti O₂,extending the absorption spectrum of Ti O₂ from ultraviolet light to visible and near-infrared light.The four kinds of Ti O₂ were prepared as photoanodes and assembled into QDSSCs.The PCE of anatase Ti O₂ cell was 3.58%,and that of black anatase Ti O₂ cell was 4.66%,showing an increase of 30%.In order to further improve the utilization rate of sunlight,dual-photoanode（D-A）QDSSCs were constructed.The PCE of double anatase Ti O₂ photoanode cell was improved to 7.23%,and that of double black anatase Ti O₂ photoanode cell was improved to 9.05%.Rutile and black rutile Ti O₂ cells showed similar performance.3.Black P25 Ti O₂ was obtained by laser modification（rutile Ti O₂+anatase Ti O₂）and QDSSCs were prepared.Compared with P25 Ti O₂,the short-circuit current density（Jsc）of the black P25 Ti O₂ sample was increased by 52%to 25.02 m A/cm²,and the cell efficiency was also greatly improved to 5.91%.The dual-anode QDSSCs device was assembled,meantime the PCE achieved 11.67%and short-circuit current density was 50.26 m A/cm².And related characterization and first-principle calculation were carried out to analyze the excellent performance of black titanium dioxide theoretically.