Graphene Quantum dots (GQDs) are used as a surface-enhanced Raman substrate for detecting target molecules with large specific surface areas and more accessible edges to enhance the signal of target molecules. The electrochemical process is used to synthesize GQDs in the solution-based process from which the SERS signals were obtained from GQDs Raman spectra. In this work, GQDs were grown via the electrochemical process with citric acid and potassium chloride (KCl) electrolyte solution to obtain GQDs in a colloidal solution-based format. Then, GQDs were characterized by transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy, respectively. From the results, SERS signals had observed via GQDs spectra through the Raman spectra at D (1326 cm−1) and G (1584 cm−1), in which D intensity is defined as the presence of defects on GQDs and G is the sp2 orbital of carbon signal. The increasing concentration of KCl in the electrolyte solution for 0.15M to 0.60M demonstrated the increment of Raman intensity at the D peak of GQDs up to 100 over the D peak of graphite. This result reveals the potential feasibility of GQDs as SERS applications compared to graphite signals.
Surface modification of Cs0.1(CH3NH3)0.9PbI3 is investigated by antisolvent‐assisted crystallization (ASAC). The perovskite solar cells (PSCs) of FTO/SnO2/Cs0.1(CH3NH3)0.9PbI3/spiro‐OMeTAD/Ag are also fabricated. It is found that isopropanol‐treated devices exhibit a power conversion efficiency (PCE) of 16.3%, which is higher than chlorobenzene‐ (11.5%) and toluene‐treated devices (12.8%). The efficiency enhancement by isopropanol treatment can be attributed to better surface coverage, larger grain size, and less pinholes confirmed by scanning electron microscopy (SEM) and X‐rays diffraction (XRD) results, indicating an increase in short‐circuit current density (Jsc). In addition, the increase in open‐circuit voltage (Voc) can be confirmed by photoluminescence (PL) spectra, which can be suggested to the reduce the nonradiative recombination loss in the isopropanol‐treated film. The wettability of perovskite films is studied by contact angle measurement, resulting in a higher hydrophobic surface from isopropanol‐treated devices. Also, the charge dynamic behavior of PSC devices is investigated by open‐circuit voltage decay (OCVD) measurement. It is found that the charge carrier lifetime of the isopropanol‐treated device is longer than that of chlorobenzene and toluene. Therefore, surface modification of perovskite by isopropanol treatment can enhance efficiency and isopropanol can be used as an alternative green antisolvent for the perovskite process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.