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Vacuum ultraviolet (VUV) light with a wavelength of 172 nm has the capacity to convert the oxygen contained metal organic precursor into metal oxide. Here, zinc acetate precursor thin film is directly converted into ZnO thin film by the irradiation of 172 nm VUV light rather than the high temperature sintering. The converting processes were demonstrated by the measurements of FTIR, XRD, SEM and XPS. And then the effect of irradiating time on the morphology, thickness and transparence of the prepared ZnO thin films was discussed. The ZnO thin film was further used as the compact layer in the photoelectrode of dye-sensitized solar cell (DSSC) to suppress the recombination processes of photogenerated electrons on the conducting glass electrode. For the different irradiation times, the photoelectric conversion efficiency of DSSC based on the compact layer prepared by the irradiation for 30 min is the highest reaching 10.27%, which is also higher than that of DSSCs without the compact layer and even with the compact layer prepared by the high temperature sintering. The uniform, dense, pinhole-free and amorphous ZnO thin film on the conducting glass substrate can be successfully prepared using the VUV irradiation technology for the compact layer of DSSCs. The ZnO compact layer prepared by the VUV light of 172 nm from zinc acetate precursor thin film shows better performance than the sintered layer for the photoelectrode of dye-sensitized solar cell. [Display omitted] • ZnO compact thin film is prepared by 172 nm VUV irradiation from zinc acetate. • ZnO thin film is used as a compact layer in photoelectrode of DSSCs. • The compact layer prepared by VUV irradiation is better than the sintered layer. [ABSTRACT FROM AUTHOR]

Quaternary Cu 2 ZnSnS 4 (CZTS) nanocrystalline thin films were in situ grown on FTO coated conductive glass by a low cost solvothermal method. The effect of the reaction time and the concentration of precursor solution on the purity and morphologies of the deposited thin films was studied. The morphology, crystal structure and composition of the deposited thin films were characterized by scanning electron microscope, high resolution transmission electron microscope, X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray spectroscopy. The pure wurtzite CZTS nanoparticles can be formed as the reaction time is 20 h. The film prepared at the optimized precursor solution concentration has uniform thickness, smooth surface and tight binding between the nanoparticles. The performance of the deposited CZTS thin films used as the counter electrode for dye-sensitized solar cells (DSSCs) was evaluated by measuring photocurrent density-voltage curves of DSSCs, electrochemical impedance spectroscopies and Tafel polarization curves of the symmetric cells. Photoelectric conversion efficiency of DSSC based on the optimized CZTS counter electrode reached 6.19%. The excellent photoelectric performance is attributed to the better surface morphology and conductive skeleton of the prepared CZTS thin film. The in situ solvothermal preparation method of the CZTS thin films for counter electrode of DSSCs is green, low cost and simple. Cu 2 ZnSnS 4 thin film in situ deposited on FTO substrate by a low cost solvothermal method has good microstructure and catalytic activity to the iodide reduction to be used as a high efficient counter electrode of dye-sensitized solar cells. Image 1 • Cu 2 ZnSnS 4 thin film is in situ deposited on FTO substrate by a low cost solvothermal method. • Cu 2 ZnSnS 4 film is well adhered to the substrate to greatly reduce the inactivation interface. • As CE of dye-sensitized solar cells, Cu 2 ZnSnS 4 film has equivalent catalytic activity to Pt. [ABSTRACT FROM AUTHOR]

BaTiO 3 is used to fabricate the electron transport layer of perovskite solar cells due to its spontaneous polarization. Li+ ions were doped into BaTiO 3 by the hydrothermal synthesis to increase the spontaneous polarization. The particle size of the as-prepared BaTiO 3 nanoparticles becomes smaller and more uniform for doping of Li+ ions with a molar ratio of 1.0 during the synthesis processes. The absorption edge shifts towards the short wavelength with the increase in the doping amount. Further, TiO 2 nanocrystalline thin film was deposited on the Li-doped BaTiO 3 thin film, the double layer was used as an electron transport layer of perovskite solar cell to indirectly demonstrate the effect of doping on the spontaneous polarization of BaTiO 3. The perovskite solar cell based on BaTiO 3 with 1.0 doping molar ratio of Li+ ions shows the highest light-to-electric conversion efficiency of 14.3% accompanying with the highest short-circuit photocurrent density. The measurements of impedance spectra and intensity modulating photocurrent spectra indicate that the photocurrent enhancement of perovskite solar cells is attributed to the spontaneous polarization enhancement of Li-doped BaTiO 3 thin films. The enhanced internal electric field in the BaTiO 3 thin layer accelerates the photogenerated electron transport in the electron transport layer of perovskite solar cell. Image 1 • The Li+ doping affects spontaneous polarization on BaTiO 3. • The spontaneous polarization in Li-doped BaTiO 3 promotes the electron transport. • Li-doped BaTiO 3 in electron transport layer improves performance of perovskite solar cell. [ABSTRACT FROM AUTHOR]