Abstract
Multiwalled carbon nanotubes (MWCNTs) have excellent electrical conductivity and good chemical stability, and are used as counter electrodes in dye-sensitized solar cells (DSSCs). The counter electrodes collect electrons from the external circuit and catalyze the redox reaction in the electrolyte. Electrocatalysis is an important step for generating energy from triiodide reduction in DSSCs. In this study, chemically treated MWCNTs were investigated for improving the photovoltaic performance of DSSCs. The MWCNTs were modified through chemical oxidation with sulfuric acid/nitric acid (H2SO4/HNO3) or potassium persulfate/sodium hydroxide (K2S2O8/NaOH). Nanocellulose (CNC) was used as a dispersant to improve the photovoltaic performance and dispersibility as an alternative material for counter electrodes in DSSCs. The counter electrodes were prepared on fluorine-doped tin oxide (FTO) glass substrates by spin coating nanofluids. Morphological and structural investigations were performed using scanning transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and Raman spectroscopy. The electrical conductivity and UV light absorption of the DSSCs were analyzed to evaluate their photovoltaic performance. The results of these analyses showed that chemical functionalization and addition of CNC were effective for increasing the electrical conductivity and UV light absorption. Finally, all result trends were the same. Increasing the dispersibility of the counter electrode was found to improve the reduction of I3− at the interface between the MWCNTs and the electrolyte, thereby, improving the energy conversion efficiency.
Highlights
Dye-sensitized solar cells (DSSCs) have attracted considerable attention owing to their high efficiency, simple fabrication process, and low production cost [1,2,3]
The highest dispersion was observed for K-carbon nanotubes (CNTs) + Cellulose nanocrystals (CNCs), i.e., CNT subjected to basic treatment followed by the addition of CNC
The photovoltaic performance showed the same trend as the energy conversion efficiency
Summary
Dye-sensitized solar cells (DSSCs) have attracted considerable attention owing to their high efficiency, simple fabrication process, and low production cost [1,2,3]. DSSCs contain a sensitizing dye, a transparent conducting substrate, nanometer-sized TiO2 film, an iodide electrolyte, and counter electrode [4]. Improved DSSC efficiency can provide enormous economic advantages [5,6,7,8,9]. The counter electrode is a significant constituent component of the DSSCs, serving an indispensable. Pt and Pt-based metallic structures are commonly used as counter electrodes because of their high electrochemical activity. Pt is relatively scarce and its use as a counter-electrode in DSSCs is limited by its high cost and potential toxicity and purity issues
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