| Cu2ZnSnS4(CZTS), SnS and CH3NH3PbI3 are widely used semiconductor materials in thin film solar cells. In this thesis, CZTS thin films were prepared by pyrolysis procedure using the methanol solution containing CuCI2, ZnCl2, SnCl2 and thiourea as the precursor solution. Electrochemical impedance spectroscopy was applied to evaluate the electrochemical catalytic activity of the CZTS thin films for redox couple of S22-/S2-, and the photovoltaic performance of the assembled quantum dot sensitized solar cells (QDSC) were measured. The WO3 thin films were prepared by spin coating-pyrolysis method using the water/DMF solution of ammonium metatungstate, and the influence of the NH4F solution on the crystal structure, surface morphology and optical band gap of WO3 thin films was investigated. The WO3 thin films were applied as the compact layer in perovskete solar cells and the photovoltaic performance of the assembled solar cells with the architecture of FTO/WO3/CH3NH3Pbl3/spiro-OMeTAD/Au were measured. The SnS thin films were prepared by close-spaced vacuum thermal evaporation using SnS powders as a source, and the influence of the substrate temperature on the surface morphology, chemical composition, crystal structure, and optical property of the SnS thin films was investigated. The PbCl2 powders were dispersed in a monodisperse isopropanol dispersions of nano-ZrO2 by ball-milling approach and the thin films were obtained by spin-coating at low temperature, subsequently, the perovskite absorber layers containing the ZrO2 scaffold layers were prepared by treating the complex film of ZrO2/PbCl2 with CH3NH3I vapour.The results revealed that the chemical composition of the pyrolysis thin films were Cu:Zn:Sn:S=2.29:1.00:1.28:4.10, near to the stoichiometric ratio of CZTS. The CZTS thin films obtained by repeating the procedure of dipping the FTO substrate into the precursor solution and heating at 380℃ for 7 cycles were uniform and porous with the pore size of 100-200 nm, and obtained the highest electrochemical catalytic activity for the redox couple of Sn2//S2- with the lowest charge transfer resistance of 64.08 Ω, and the corresponding QDSC gave a short circuit photocurrent density (Jsc) of 12.96 mA·cm-2, open circuit voltage (Voc) of 0.52 V, fill factor (FF) of 0.38, and the photovoltaic conversion efficiency (η) of 2.56%. The WO3 thin films prepared by spin coating-pyrolysis were dense and pin-hole free, and the perovskite solar cell with the compact WO3 layer gave a Jsc of 17.77 mA cm-2, a Voc of 0.64 V, a FF of 0.56 and η of 6.39%. Treating the WO3 thin films with NH4F solution had no influence on the crystal structure and the optical band gap of the thin films, however, a few small particles were appeared on the surface of the thin films and the photovoltaic performance of the corresponding solar cells was not improved. The ratio of Sn/S in SnS thin films prepared by close-spaced vacuum thermal evaporation at the substrate temperature of 300℃,350℃ and 400℃ was near to 1:1, the prepared SnS thin films with the gear-like sheet appearance were well crystallized, and a preferred orientation along (111) plane appeared. The SnS thin films showed with the p type conduction. The serration architecture appeared obviously in the edge of the SnS sheet, the strongest peak at 2θ=31.63° was broadened, many shoulder peaks were observed and the optical absorption edge had a red shift with the substrate temperature increased. The CH3NH3PbCl3 generated and the chemical composition of the thin film was Zr:Pb:Cl:I=1.28:100:2.32:0.20 when ZrO2/PbI2 thin films were treated with CH3NH3I vapour for 10 min, after additional 50 min of CH3NH3I vapour exposure, the main phase CH3NH3Pbl3 was obtained with the dense, uniform, and smooth appearance. |
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