Fabrication of cellulose paper-based counter electrodes for flexible dye-sensitized solar cells.

Here, we introduce the synthesis and deposition of organic/inorganic composite ink on cellulose paper using a rapid ultrasonic spray deposition approach that can be incorporated as a counter electrode (CE) in flexible dye-sensitized solar cells (FDSSCs). The composite ink comprised a copper indium sulfide (CuInS 2 ) nanostructure ink and dispersion of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) in water. Fabricated counter electrodes are biodegradable, environment-friendly, flexible, and economical and meet the requirements for sustainable green energy. To evaluate the catalytic activities and power conversion efficiencies of DSSCs, the produced CuInS 2 /PEDOT:PSS composite ink-based CEs were compared with PEDOT:PSS counter electrodes. Cyclic voltammetry studies found that CuInS 2 /PEDOT:PSS had a greater cathodic charge transfer current density ( J c ) (-1.23 mA cm -2 ). Moreover, it was found that the potential separation values are small, which indicate a stronger catalytic activity than PEDOT:PSS counter electrodes. The observed exchange current density ( J 0 ) was 3.98 mA cm -2 , while the limiting current density ( J lim ) increased to 45.7 mA cm -2 , indicating a fast redox diffusion rate of the CuInS 2 /PEDOT:PSS CE. The photovoltaic performances of CuInS 2 /PEDOT:PSS and PEDOT: PSS-based DSSC's were measured and determined to be 5.66% and 4.41%, respectively, while the performance of CuInS 2 /PEDOT:PSS FDSSC composed of cellulose paper was 1.06%.