Chengwu Shi

Preparation of SnS thin films with gear-like sheet appearance by close-spaced vacuum thermal evaporation

SnS thin films with gear-like sheet appearance were successfully prepared by close-spaced vacuum thermal evaporation using SnS powders as a source. The influence of substrate temperature on the surface morphology, chemical composition, crystal structure and optical property of SnS thin films was investigated by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction and ultraviolet–visible–near infrared spectroscopy. The results revealed that serration architecture appeared obviously in the edge of the SnS sheet and the strongest peak at 2𝜃 =31.63∘ was broadened and many shoulder peaks were observed with increasing substrate temperature. The atomic ratio of Sn to S increased from 1:1.08 to 1:1.20, the grain size became slightly smaller and the optical absorption edge had a blueshift in the SnS thin film with decreasing substrate temperature.

Br-Doping CH3NH3PbI3−xBrx Thin Films for Efficient TiO2 Nanorod Array Perovskite Solar Cells

CH3NH3PbI3-xBrx thin films with different Br contents were successfully prepared on TiO2 nanorod array using 1.7 M PbI2 · DMSO complex solution and 0.465 M CH3NH3x(x = Br, I) precursors with different CH3NH3Br contents (molar ratios) by sequential deposition method. The influence of CH3NH3Br contents on the chemical composition, crystallinity, optical absorption and surface morphology of the CH3NH3PbI3-xBrx thin films was systematically investigated, and the photovoltaic performance of the corresponding TiO2 nanorod array perovskite solar cells was evaluated. The results revealed that the CH3NH3PbI3-xBrx solar cells using CH3NH3x precursors with 5% CH3NH3Br exhibited the best photoelectric conversion efficiency (PCE) of 16.47%, along with an open-circuit voltage (Voc) of 1.02 V, short-circuit photocurrent density (Jsc) of 20.99 mA · cm-2 and fill factor (FF) of 0.77, and the average PCE of 16.06 ± 0.52%, along with Voc of 1.02 ± 0.01 V, Jsc of 20.41 ± 0.58 mA · cm-2 and FF of 0.77 ± 0.01 under illumination of simulated AM 1.5 sunlight (100 mA cm-2).

420 nm thick

The rutile TiO2 nanorod arrays with 240 nm in length, 30 nm in diameter, and in areal density were prepared by the hydrothermal method to replace the typical 200–300 nm thick mesoporous TiO2 thin films in perovskite solar cells. The CH3NH3PbI3−x Br x capping layers with different thicknesses were obtained on the TiO2 nanorod arrays using different concentration complex precursor solutions in DMF and the photovoltaic performances of the corresponding solar cells were compared. The perovskite solar cells based on 240 nm long TiO2 nanorod arrays and 420 nm thick CH3NH3PbI3−x Br x capping layers showed the best photoelectric conversion efficiency (PCE) of 15.56% and the average PCE of 14.93±0.63% at the relative humidity of 50%–54% under the illumination of simulated AM 1.5 sunlight ().