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All Journal Makara Journal of Technology International Journal of Renewable Energy Development
Arramel, Arramel
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Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering Materials Science & Nanotechnology Mechanical Engineering

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Spectroscopic Contrast of Diarylethene Molecules on Octanethiol Monolayer Arramel, Arramel; Kudernac, Tibor; Katsonis, Nathalie; Feringa, Bernard Lucas; van Wees, Bart Jan
Makara Journal of Technology Vol. 21, No. 2
Publisher : UI Scholars Hub

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Abstract

We present a systematic scanning tunneling microscopy (STM) study of bias-dependent imaging of disulfur diarylethene (2S-DE) molecules on octanethiol (C8) monolayer at room temperature. In a rigid confinement of the C8 matrix, we did not observe any significant variation in the appearance of the 2S-DE. On the contrary, a reversal in the apparent height of the 2S-DE was present when the molecule was situated on a gold vacancy island. We attributed this finding to the presence of a new electronic state that became accessible for a tunneling event. In addition, the C8 surface structure underwent a reversible phase transformation from √3 x √3 R30º hexagonal to c(4x2) square superlattice when the bias voltage was reduced from -825 mV to -425 mV or vice versa. Under a finite bias voltage, an appreciable topographic variation of the 2S-DE signature was demonstrated for the first time. This finding can be ascribed to a finite overlap of the associated wave functions that occurred between the tip state and the 2S-DE molecular energy level. We believe that physical insight on the bias-dependent imaging of organic molecules on solid surface is important towards the advancement of molecular electronics-based devices.
Natural pigment-based dye-sensitized solar cells utilizing Caulerpa racemose and Gymnogongrus flabelliformis as photosensitizers Unwakoly, Semuel; Liliasari, Liliasari; Hartati, Sri; Munawaroh, Heli Siti H; Arramel, Arramel; Rusliani, Prima Fitri; Prima, Eka Cahya
International Journal of Renewable Energy Development Vol 14, No 3 (2025): May 2025
Publisher : Center of Biomass & Renewable Energy (CBIORE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.61435/ijred.2025.61083

Abstract

This research examines natural dyes' chemical and physical characteristics for potential use in dye-sensitized solar cells (DSSCs). Chlorophyll pigments were extracted from two macroalgae species, Caulerpa racemosa and Gymnogongrus flabelliformis, and analyzed using absorbance spectroscopy, band gap energy calculations, and dye-sensitized solar cell performance evaluation. Fourier Transform Infrared (FTIR) characterisation was used to identify the pigments contained in the dye. The absorbance spectra of chlorophyll pigments extracted from both macroalgae species showed broad peaks at 400–800 nm wavelengths, with Gymnogongrus flabelliformis showing the highest absorbance peak at 403 nm. The redox potential analysis for both macroalgae species showed energy gaps (HOMO/LUMO) of 1.3 eV, 1.4 eV, 2.3 eV, and 2.4 eV, respectively, indicating that these natural dyes are suitable for use in DSSC applications. DSSC devices were fabricated using components such as liquid electrolyte, mesoporous titanium dioxide (TiO₂) photoelectrode, reduced graphene oxide (rGO) as counter electrode, and ITO glass as conductive substrate. Meanwhile, to evaluate how well the photovoltaic system worked, we looked at short-circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and overall photoelectric conversion efficiency (η). The results showed that the highest performance for Gymnogongrus flabelliformis was Jsc 0.041 mA/cm², Voc 0.28 V, FF 0.239, and η 0.020%, while the highest performance of Caulerpa racemosa was Jsc 0.023 mA/cm², Voc 0.46 V, FF 0.244, and η 0.019%. These findings indicate the potential for using and developing natural dyes derived from these two macroalgae species in DSSC technology. This research offers insight into the feasibility of marine-derived pigments as a sustainable and environmentally friendly alternative for photovoltaic applications.
Co-Authors Eka Cahya Prima Feringa, Bernard Lucas Katsonis, Nathalie Kudernac, Tibor Liliasari , Munawaroh, Heli Siti H Rusliani, Prima Fitri Sri Hartati Unwakoly, Semuel van Wees, Bart Jan