S 4700

The absorbance and SPR of nano-Au colloids were determined through UV–Vis, Zeta potential and particle distribution through a Zetasizer (Malvern Zetasizer, Nano-ZS90, Worcestershire, UK), particle shapes and sizes through SEM (HITACHI, S-4700, Tokyo, Japan), and the constituent elements through X-ray (HITACHI, S-4700, Tokyo, Japan) [19 (link)].
The suspension stability of nano-Au colloids can be determined by their Zeta potential [20 ,21 (link)]. A high Zeta potential indicates an even distribution of nanoparticles in DW and high suspension stability, whereas a low Zeta potential suggests low suspension stability and causes nanoparticles to collide with each other and precipitate. In addition, because like electric charges repel each other, a Zeta potential with an absolute value of 30 mV indicates high suspension stability in nanoparticles [22 (link)].

A Fourier transform infrared spectrometer (FT−IR, Vertex 70/Raman, Bruker, Billerica, MA, USA) was used to characterize the functional groups in the polymer membrane samples. The morphological structure of membranes was investigated using a scanning electron microscope (SEM, S-4700, Hitachi S-4700, Tokyo, Japan) and a transmission electron microscope (TEM, Tecnai G2 F30 S-Twin, AP Tech, Incheon Incheon, Korea). The membrane samples were immersed in 1 M Na₂WO₄ solution for 24 h at 30 °C and dried in a vacuum oven after washing with DI water to prepare TEM samples. A thermogravimetric analyzer (TGA, TA Instruments SDT Q600, New Castle, DE, USA) was used to examine the tensile strength and thermal stability of the membranes. The TGA temperature was raised at 10 °C min⁻¹ until 600 °C with nitrogen flowing.

Morphological analysis of liposomes was performed by freeze-fracture electron microscopy. The investigations were performed while using a field emission-scanning electron microscope (FE-SEM; Hitachi S-4700, Tokyo, Japan), operating at 5 kV, and in ultra-high-resolution mode. For freeze-fracture electron microscopy measurements, the liposomes were immediately frozen while using a propane jet-freeze device JFD 030 (BAL-TEC, Balzers, Liechtenstein). Subsequently, the samples were transferred to freeze-fracture/etching/coating system MED 020 GBE (BAL-TEC) using a high vacuum cryo-transfer system VTC-100 (BAL-TEC). The samples were kept below −120 °C in a protected atmosphere during the examination. The frozen samples were fractured using a metal knife, etched for 1 min. at −105 °C and coated with platinum for 70 s at 70 mA. Finally, the samples were observed while using a cryogenic FE-SEM (Hitachi S-4700) at −120 °C.

The infilling of gel electrolyte in the pores of the MWCNT electrodes is investigated by means of field emission scanning electron microscopy (SEM, Hitachi, S-4700), energy dispersive spectroscopy (Hitachi, S-4700) and BET (NOVA 2200e). Electrochemical characterization, including CV, GCD, and EIS, is performed using a VMP3 multichannel potentiostat (VMP3, Bio-Logic, USA) and a potentiostat (Versastat 3, Princeton Applied Research, USA) in the two-electrode mode at room temperature. Contact electrodes, i.e., Cu tapes, are adhered to the FSSC devices for an easy connection to the probe and convenient tandems. The thicknesses of the MWCNT electrodes were measured using the cross-sectional SEM and a micrometer. Calculations of specific capacitance and energy and power densities are discussed in detail in Supplementary Note 1.

The PL measurements (RPM2000, Accent Optical Technologies, Bend, OR, USA) were conducted with a 532 nm laser and atomic force microscopy (XE-100, Park Systems, Suwon, Korea) to analyze the characteristics of the QDs. Energy-dispersive X-ray spectroscopy (EDX, S-4700, Hitachi, Tokyo, Japan) was then performed for compositional analysis of the CZTSSe absorber films. The structural properties of the absorber films were also analyzed by X-ray diffraction (XRD, X’pert-APD, Philips, Eindhoven, Netherlands) with CuKα radiation, and Raman spectroscopy was performed with laser excitation at 514 nm. The optical properties of the MgF₂ and MgF₂/QD layers were measured using a UV-vis-IR spectrometer (Cary 5000, Agilent Technologies, Santa Clara, CA, USA). Scanning electron microscopy (SEM, S-4700, Hitachi, Tokyo, Japan) was performed for the cross-sectional analysis of the CZTSSe solar cells, and their parameters were measured with a class AAA solar simulator (WXS-155S-L2, Wacom, Tokyo, Japan) under conditions of AM 1.5 G, 100 mW/cm², and 25 °C. Thickness measurements of the thin-films were also performed using the SEM. The EQEs (QEX7, PV Measurements, Boulder, CO, USA) were determined to analyze the short-wavelength responses and bandgap energies of the CZTSSe solar cells.

Energy-dispersive X-ray spectroscopy (EDX) (S-4700, Hitachi, Tokyo, Japan) and X-ray photoelectron spectroscopy (XPS) (VG Multilab 2000, Thermo Fisher Scientific) were performed to assess changes in the surface chemical composition of the specimens due to plasma treatment. To compare the changes in hydrophilicity, 4 µL of distilled water was dropped on the surface; after 10 s, the angle between the surface and water droplet was measured using a video contact angle meter (Phoenix 300, SEO, Kromtek, Selangor, DE, Malaysia). The average of the contact angles was calculated from the analysis of three specimens per group. Changes in the surface structure of the specimens, as well as bacterial and cell adhesion following the plasma treatment were observed using a scanning electron microscope (SEM) (S-4700, Hitachi) after coating the specimens with gold-palladium alloy using a Cressington sputter coater (108 auto, Cressington Scientific Instruments, Watford, UK).