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In this study, the sol–gel method was used to prepare ZnO seed layer for synthesizing ZnO nanorods, and we would investigate the effects of different Zn(CH3COO)2 and C6H[Formula: see text]N4 concentrations on the synthesized characteristics of ZnO nanorods. First, the ZnO gel was dipped on the surface of the [Formula: see text]-type [Formula: see text] wafer as a seed layer. Then, the hydrothermal method with different Zn(CH3COO)2 and C6H[Formula: see text]N4 concentrations as precursors was used to synthesize ZnO nanorods on [Formula: see text]-type [Formula: see text] wafer. X-ray diffraction (XRD) pattern, focused ion beam-field emission scanning electron microscopy (FIB-FESEM) and photoluminescence (PL) spectrometry were employed to observe and analyze the crystal properties, surface morphologies, and optical properties of the prepared ZnO seed layer and synthesized ZnO nanorods. [Formula: see text]C and 60 min were used as the synthesis temperature and time, and we found that Zn(CH3COO)2 and C6H[Formula: see text]N4 concentrations had an apparent effect on the height, diameter, total surface area, total volume, density, and PL property of ZnO nanorods. The maximum PL emission intensity of ZnO nanorods presented in the samples with Zn(CH3COO)2 and C6H[Formula: see text]N4 concentrations of 0.2 M. The results of XRD patterns suggest that ZnO nanorods have the property of [Formula: see text]-axis preferred orientation. We showed that the different Zn(CH3COO)2 concentrations had large effects on the average height, average diameter, aspect ratio, total surface area (S, nm[Formula: see text], total volume (V, nm[Formula: see text], S/V ratio, and PL property of ZnO nanorods.

This study explores the influence of molar ratio of the synthetic solution of methylammonium iodide (MAI) and PbI2 on perovskite solar cells. The complete perovskite crystals must be produced in a low-humidity environment. The substrate is spin-coated in the adjusted MAPbI3 synthesis solution and annealed by using a nitrogen furnace tube to form perovskite crystals. During the crystallization of MAPbI3, some of the PbI2 remains, which improves the efficiency of the perovskite solar cell. Therefore, we adjust the molar concentration of MAI to find the appropriate amount of the PbI2 residual. We fix the MAI molar concentration at 1 M and adjust the PbI2 molar concentration from 0.8 M to 1.4 M. The molar ratios of MAI and PbI2 are, then, 1:0.8, 1:1, 1:1.2, and 1:1.4, respectively. Then, we use UV–vis, FE-SEM, and photoelectric conversion efficiency (PCE) measurements for comparing the growth of perovskite crystals and their photoelectric characteristics. The results show that 1.2 M of PbI2 is the most appropriate concentration for perovskite solar cells among the adjusted concentrations.

The doctor blade coating method is used to prepare dye-sensitized solar cells (DSSCs) and dope the original titanium dioxide (TiO2, P25) photoanode (PA) with single-layer graphene (G), graphene quantum dots (GQDs), and gold (Au) nanoparticles in this research. The results show that doping PAs with G, GQDS, and Au effectively increases the short-circuit current density ([Formula: see text], conversion efficiency ([Formula: see text]), and decreases the internal structure impedance ([Formula: see text]) of DSSCs. [Formula: see text] increases from 13.62 to 17.02, 15.22, 16.05 mA/cm2, while [Formula: see text] (%) increases from 6.36 to 7.50, 7.08, 7.04% when doping G, GQDs, and Au, respectively. The analysis of Electrochemical Impedance Spectroscopy (EIS) reveals that the doping decreases [Formula: see text] from 11.28 to 8.36, 8.78, 8.54 [Formula: see text], respectively. Then, the titanium dioxide (TiO[Formula: see text]-doped G-GQDs, G-Au, and QDs-Au on DSSCs influence [Formula: see text] that increases to 5.45, 15.37, and 15.31 mA/cm2, respectively. In this case, the values of [Formula: see text] are found to be 7.21%, 7.35%, and 7.00%, while those of [Formula: see text] are 8.44, 8.63, and 9.18 [Formula: see text]. The values of [Formula: see text] and [Formula: see text] are highest but that of [Formula: see text] are lowest when doping with G, which proves that the photoanode of the DSSC effectively activates the photogenerated electrons in the film by doping single-layer graphene and TiO2 captures its electrons through graphene. The decreasing electron–hole recombination rate allows the photogenerated electrons to be quickly transferred to the external circuit. As a result, the efficiency of DSSCs is improved.

The scattering layer in the TiO2 photoanode (PAs) of dye-sensitized solar cells (DSSCs) is doped with single-layer graphene (G), and DSSC is prepared by doctor blade coating method. A small amount of graphene (0.0016 wt.%) in a graphene aqueous solution (G-AS) and a G-TiO2 paste was prepared to make 2–20 wt.% of G-AS in the deionized water (DIW). The UV-Vis measurement results show that the TiO2 scattering layers doped with graphene effectively improve the visible light absorption intensity of DSSC PAs and increase the current density (Jsc) from 13.84 mA/cm2 to 16.20 mA/cm2. The Electrochemical Impedance Spectroscopy (EIS) measurement showed that the internal structural impedance Rk [Formula: see text] decreased from 12.086 [Formula: see text] (without graphene doping) to 9.875 [Formula: see text] at 5 wt.% of the graphene doping. The photoelectric conversion efficiency (PCE) increased from 6.56% of the original un-doped graphene to the maximum PCE value of 7.57% at 5 wt.%. The results show that the best PCE is obtained when the concentration of G-AS is 5 wt.%.