Influence of Poly(N-vinylcarbazole) as a Photoanode Component in Enhancing the Performance of a Dye-Sensitized Solar Cell

Abstract

Increasing the dye adsorption and minimization of charge recombination are pivotal in improving the efficiency of a dye-sensitized solar cells (DSSCs). In the present investigation, these two effects have been accomplished through the introduction of poly(N-vinylcarbazole) (PVK) as an auxiliary component of the TiO2 photoanode in a N719 dye-based DSSC. TiO2/PVK hybrid nanocomposites were prepared by simple blending of TiO2 with small quantities of PVK (0.3–1.3 wt %) in the presence of PEG20000, acetylacetone, and Triton X-100. X-ray diffraction data revealed that the crystalline properties of TiO2 were not altered by the presence of PVK. The porosity and surface roughness of TiO2 were enhanced by the addition of PVK. Spin-coated TiO2–PVK nanocomposite films showed highly enhanced dye adsorption in comparison to pristine TIO2 films which had been attributed to an increase in the basicity of the TiO2 surface. The N719 dye-sensitized TiO2/PVK photoanodes were assessed for their performance in a DSSC assembled with the I–/I3– redox electrolyte and sputtered Pt as counter electrode. The quantity of PVK in the nanocomposite was optimized by evaluating the photovoltaic performance. A maximum power conversion efficiency of 7.10% was achieved with a 0.9 wt % PVK loaded TiO2, which was 58% greater than that of the pristine TiO2 cell (4.48%). Impedance data showed a very low charge-transfer resistance of 3.79 Ω and a high electron lifetime of 31.41 ms, implying an effective reduction in the back electron transfer.