This work demonstrates the electrochemical synthesis of nanoscale gold particles using a surfactant solution. Tetradodecylammonium bromide (TTAB) surfactant was applied to stabilize the gold clusters. Experimental results reveal that the size of the produced gold nanoparticles is controlled by the amount of TTAB surfactant, the current density, and the growth temperature. The size of the gold nanoparticles can be controlled in the range <mml:math display="inline"><mml:mrow><mml:mn>58.3</mml:mn><mml:mo>–</mml:mo><mml:mn>8.3</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>nm</mml:mi></mml:mrow></mml:math>58.3–8.3nm . The particle size decreases as the amount of TTAB increases from <mml:math display="inline"><mml:mrow><mml:mn>1</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mtext>to</mml:mtext><mml:mspace width="0.3em"></mml:mspace><mml:mn>90</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>mg</mml:mi></mml:mrow></mml:math>1to90mg . The optimal current density in this study was <mml:math display="inline"><mml:mrow><mml:mn>3</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>mA</mml:mi><mml:mo>∕</mml:mo><mml:msup><mml:mi>cm</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>3mA∕cm2 . The size of the produced nanoparticles increases linearly with the growth temperature from <mml:math display="inline"><mml:mrow><mml:mn>25</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mtext>to</mml:mtext><mml:mspace width="0.3em"></mml:mspace><mml:mn>60</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>25to60°C . The gold nanoparticles were observed by transmission electron microscopy, ultraviolet-visible spectrometry, and X-ray photoelectron spectroscopy. A mechanism for electrochemically controlling the size of the gold nanoparticles is presented.

The properties of perovskite solar cells (PSCs) fabricated using various solvents was studied. The devices had an indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)/CH₃NH₃PbI₃ (fabricated by using various solvents)/fullerene (C₆₀)/bathocuproine (BCP)/silver (Ag) structure. The solvents used were dimethylformamide (DMF), γ-butyrolactone (GBL), dimethyl sulfoxide (DMSO), a mixture of DMSO and DMF (1:1 v/v), and a mixture of DMSO and GBL (DMSO: GBL, 1:1 v/v), respectively. The power conversion efficiency (PCE) of the device fabricated using DMF is zero, which is attributed to the poor coverage of CH₃NH₃PbI₃ film on the substrate. In addition, the PCE of the device made using GBL is only 1.74% due to the low solubility of PbI₂ and CH₃NH₃I. In contrast, the PCE of the device fabricated using the solvents containing DMSO showed better performance. This is ascribed to the high solubilization properties and strong coordination of DMSO. As a result, a PCE of 9.77% was obtained using a mixed DMSO:GBL solvent due to the smooth surface, uniform film coverage on the substrate and the high crystallization of the perovskite structure. Finally, a mixed DMSO: DMF:GBL (5:2:3 v/v/v) solvent that combined the advantages of each solvent was used to fabricate a device, leading to a further improvement of the PCE of the resulting PSC to 10.84%.

This investigation demonstrates the rapid synthesis of a large quantity of uniform-sized gold nanocubes by an electrochemical method, using a surfactant solution and acetone. A redshift is observed in ultraviolet-visible absorption spectra as the shape of gold nanoparticles changes from spherical to cubic. The selected area electron diffraction patterns reveal that the gold nanocubes are single crystalline with lattice constant <mml:math display="inline"><mml:mrow><mml:mi>a</mml:mi><mml:mo>=</mml:mo><mml:mn>4.068</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi mathvariant="normal">Å</mml:mi></mml:mrow></mml:math>a=4.068Å . The nanocube edge is about <mml:math display="inline"><mml:mrow><mml:mn>30</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>nm</mml:mi></mml:mrow></mml:math>30nm long. The gold nanocubes are truncated structures, as revealed by high-resolution transmission electron microscopy analysis. The effect of acetone addition on the shape of particles is also discussed.

This article demonstrates changes in the structures of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) with the addition of organic additives. The mechanisms of PEDOT: PSS are analyzed using X-ray photoelectron spectroscopy (XPS), cross-sectional images obtained from scanning electron microscopy (SEM), and contact angles. In this paper, a bond-breaking reaction and phase separation are successfully found to occur between PEDOT: PSS molecules and the organic additives. Our research also finds that this bond-breaking reaction and phase separation exist in the PEDOT: PSS–sorbitol–maltitol film at the same time. The addition of organic additives will improve the optical properties and the moisture stability of PEDOT: PSS films.

In this study, we prepared different shapes of gold nanoparticles by seed-mediated growth method and applied them on the photoelectrodes of dye-sensitized solar cells (DSSCs) to study the surface plasma resonant (SPR) effect of gold nanoparticles on the photoelectrodes of dye-sensitized solar cells. The analyses of field emission scanning electron microscopy show that the average diameter of the spherical gold nanoparticles is 45 nm, the average length and width of the short gold nanorods were 55 and 22 nm, respectively, and the average length and width of the long gold nanorods were 55 and 14 nm, respectively. The aspect ratio of the short and long gold nanorods was about 2.5 and 4, respectively. The results of ultraviolet–visible absorption spectra show that the absorption wavelength is about 540 nm for spherical gold nanoparticles, and the absorption of the gold nanorods reveals two peaks. One is about 510 to 520 nm, and the other is about 670 and 710 nm for the short and long gold nanorods, respectively. The best conversion efficiency of the dye-sensitized solar cells with spherical gold nanoparticles and short and long gold nanorods added in is 6.77%, 7.08%, and 7.29%, respectively, and is higher than that of the cells without gold nanoparticles, which is 6.21%. This result indicates that the effect of gold nanoparticles on the photoelectrodes can increase the conductivity and reduce the recombination of charges in the photoelectrodes, resulting in the increase of conversion efficiency for DSSCs. In addition, the long gold nanorods have stronger SPR effect than the spherical gold nanoparticles and short gold nanorods at long wavelength. This may be the reason for the higher conversion efficiency of DSSCs with long gold nanorods than those of the cells with spherical gold nanoparticles and short gold nanorods.