Enhancing the conductivity of bacterial cellulose/polyvinyl alcohol composite for the development of flexible transparent electrodes

Abstract

This study addresses the key components required to enhance the power conversion efficiency of organic solar cells. The first part of the research focuses on incorporating silver nanoparticles into the PEDOT:PSS layer to enhance light absorption. The silver nanoparticles were synthesised using the chemical reduction method. Then incorporated into the PEDOT:PSS liquid to make a blend of PEDOT:PSS and silver nanoparticles. The blend was coated on top of a glass substrate using the spin coating method. Characterisation techniques such as XRD, TEM, SEM, Raman, and UV-vis were used. TEM analysis revealed that the silver nanoparticles synthesised were spherical and ranged in size from 10 to 70 nm. The UV-visible spectroscopy confirmed the presence of the silver nanoparticles, showing an absorption peak at 389 nm. Furthermore, UV-vis analysis was conducted to evaluate the absorption of both the pristine PEDOT:PSS and the PEDOT:PSS with silver nanoparticles. The findings showed an enhanced absorption in the PEDOT:PSS blend with silver nanoparticles, demonstrating that the incorporation of silver nanoparticles into the PEDOT:PSS improved its light absorption properties. The second part is directed towards fabricating a transparent, flexible, conductive substrate that will serve as an anode for the organic solar cell. Bacterial cellulose synthesised using kombucha tea through static cultivation was combined with polyvinyl alcohol to make flexible, lightweight and transparent substrates. The composite substrates were made conductive by adsorbing multi-walled carbon nanotubes onto the substrate using the adsorption method. Different concentrations of multi-walled carbon nanotubes were explored on the composite films. Characterisation techniques such as UV-vis spectroscopy, SEM, TEM, XRD, TGA and electrical conductivity measurements of the individual components and the final films were assessed. The substrate with a 0.05% concentration of multi-walled carbon nanotubes showed the highest conductivity. The TGA results showed that the addition of polyvinyl alcohol to bacterial cellulose resulted in composite substrates with lower degradation at temperatures 213- 467 ℃, as compared to pure bacterial cellulose which is due to the structural degradation of the composite substrates. The UV-vis transmittance spectra indicated that using a higher concentration of multi-walled carbon nanotube dispersion during fabrication resulted in electrically conductive transparent substrates with reduced transparency.