Fabrication of highly efficient and cost-effective dye-sensitized solar cells using ZnO/MWCNT nanocomposite as photoanode

In the present study, a novel cost-effective and efficient configuration of dye-sensitized solar cell (DSSC) with zinc oxide–multi-walled carbon nanotube (ZnO-MWCNT) composite has been constructed. The ZnO nanoparticles are synthesized by using microwave irradiation–assisted route and subsequently grinded with acid-treated MWCNTs at different concentrations. The ZnO/MWCNT nanocomposites along with N719 dye are used as photoanodes while Pt is used as counter electrode to construct DSSC devices. XRD results confirm polycrystalline ZnO nanoparticles, while SEM and TEM analyses reveal the homogeneous formation of the ZnO/MWCNT nanocomposites with 10–20-nm ZnO nanoparticles. EDS results confirm the Zn, O and C presence, while FTIR confirms the ZnO/MWCNT interactions. UV–visible spectral analyses reveal a reduction in the band gap energy with the increase of MWCNT concentrations, whereas PL result implies inhibition of electron–hole pair recombination process. Photovoltaic investigations indicate that the ZnO/MWCNT (0.5) photoanode delivers a high photoconversion efficiency (PCE) of 8.85% which is 3.85 times better than that of bare ZnO (2.32%). The electrochemical impedance study also reveals that the composite electrode shows high catalytic activity and high electron lifetime. The high photoconversion efficiency in terms of pore size, incident photon-to-current conversion efficiency and optical absorption quality has been discussed.