Preparation And Study Of Quantum Dots Sensitized Silver Nanowires Composite

Quantum dot-sensitized solar cells (QDSSC) have a high theoretical photovoltaic conversion efficiency, but its actual conversion efficiency is still low and far behind the Dye-sensitized solar cell after many years of research. To improve the performance of QDSSC, we must explore a new photoanode materials which have higher light absorption and ligher electron transfer rate. Thus, high conductive silver nanowires (AgNWs) have been utilized for electron transport matrix in this paper. The CdSe/CdS core/shell quantum dots is selected as a quantum dot-sensitizer. Eventually, we prepare the quantum dots sensitized silver nanowires composite (QDs-PATP@AgNWs), and a stable electron transfer channel from QDs to the AgNWs by ?-conjugated PATP ligands.By controlling the reaction time, we prepared a series of different CdSe/CdS core/shell quantum dots. The results show that with the increase of reaction time the particle size of quantum dots increased and the emission wavelength have an obvious red shift.The ligand of original quantum dots is oleic acid (OA), the chemically inert surface made it hard for QDs to attach to AgNWs. Therefore, a new ligand 4-Aminothiophenol (PATP) capped QDs have been successfully prepared by ligand-exchange approach. QDs can easily and effectively absorb-SH due to the higher affinity of Cd-S, and-NH2 was exposed on the surface of QDs. The FT-IR spectra, HR-TEM images,UV-vis absorption spectra and Fluorescence spectra showed that QDs-PATP had been prepared, and they still had good optical property; The result of Acid base titration showed that with the time of ligand exchange increasing, the -NH2 on the surface of QDs and fluorescence intensity of QDs increased till to 24 h.AgNWs was prerared by ethylene glycol reduction method. And we studied the influence of different reaction conditions on its morphology. The SEM images, UV-vis absorption spectra, XRD spectra and HR-TEM images showed that AgNWs was pure and with uniform diameter.-NH2 exposed on the surface of QDs can attached to AgNWs by self-assembly. HR-TEM images and EDS spectra showed that the QDs-PATP was successfully attached to AgNWs; UV-vis absorption spectra and Fluorescence spectra showed that QDs-PATP@AgNWs could absorb light and released it as an electric rather than a photon. It is proved that QDs-PATP@AgNWs could used for photovoltaic materials.We used QDs-PATP@AgNWs for the solar photoanode materials, its photovoltaic conversion efficiency was much higher than the mixture of QDs-OA and AgNWs. This result proved that PATP formed a high-performance electron transfer channel from QDs to the AgNWs. Furthermore, we studied the influence of the concentration of QDs on its photovoltaic conversion efficiency. The photovoltaic conversion efficiency could up to 3.34% with the concentration of QDs.