Preparation Of Monodispersed PbS Quantum Dots On Nanoporoussemiconductor Thin Film By Two-phase Method And Application In Solar Cells

The quantum dot-sensitized solar cells attract more and more researchers’attention because of the advantage of clean energy and low cost. In the thesis, the novel two-phase method was developed to in situ prepare monodispered PbS quantum dots on nanoporous semiconductor thin film, and they were assembled into solar cells. The major research work includes the following aspects:Exploring the synthesis condition of preparation monodispersed PbS quantum dots by the2-phase method, in the method, the two phases refer:o an oil phase consisting of S2-ions(phase Ⅰ) and an aqueous solution(phase Ⅱ). The S2-ions contained in the oil phase preferred to ransfer through the oil/aqueous interfaces, and contacted with Pb2+ions on the nanoporous thin film within the phase Ⅱ. We aimed to find the optimum experimental condition adjust the size of the PbS quantum dots. A series of characterization such as SEM、 XRD、UV-vis-NIR absorbtion shows that PbS quantum dots can reach5-7nm when the volume ratio of ethylene glycol and deionized is1:2.In the solar cells we use the PbS quantum dot-sensitized nanoporous thin film as anodes, polysulfide as electrolyte, PbS as counter electrode to study photovoltaic performance. In order to improve the conversion efficiency of the solar cells, titanium tetrachloride and zinc sulfide solution were applied to modify the surface of working electrode. They both can greatly improve the photocurrent and conversion efficiency according to photocurrent-voltage curve, EIS, IMPS/IMVS. The2.2times higher photocurrent was obtained after the surface treatment. Some comparison was made between2-phase and SILAR method.