Aligned carbon nanotube/polymer hybrid electrolytes for high performance dye sensitized solar cell applications

Abstract

Novel multiwalled carbon nanotube (MWCNT) filled poly(ethylene oxide) (PEO) and poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) composite electrolytes were successfully prepared for solid state dye sensitized solar cell application. The prepared composite membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetry (TGA), UV-visible spectroscopy, electrochemical impedance spectroscopy (EIS) and linear steady state voltammetry (LSV) measurements. The incorporated MWCNTs were electrically aligned by applied external DC electric field of 440 V/cm. The alignment of MWCNTs in PEO/PVDF-HFP matrix was confirmed by wide angle X-ray diffraction (WAXD) and Raman spectroscopy. The ionic conductivity doubled upto 5.72 mS/cm for aligned MWCNT-PEO/PVDF-HFP electrolyte in comparison to the electrolyte containing unaligned-MWCNT. It was observed from linear steady state voltammograms that the apparent diffusion coefficient was increased upto 7.1 x 10 -9 cm 2 /s (I -) for the electrically aligned MWCNT incorporated electrolyte. The optimal composition of polymer nanocomposites (1 wt% of MWCNT in 4:6 wt% of PEO/PVDF-HFP) were used as electrolyte for the fabrications of solid state dye sensitized solar cells (DSSCs). The DSSC with electrically aligned MWCNT-PEO/PVDF-HFP electrolyte showed the higher photo conversion efficiency of about 4 % under the illuminations of 100 mW/cm 2 , while the device based onunaligned MWCNT based electrolyte gave 3.2%. The enhancement was also confirmed by the electrochemical impedance spectra analyses of DSSC that showed lower diffusion resistance (R dif ) and charge transfer resistance (R ct ). The stability of the device was studied using chronoamperometry technique under several on-off cycles. Graphical AbstractElectrically aligned MWCNT/PEO/PVDF-HFP nanocomposite electrolyte membrane based solid state dye sensitized solar cell shows a power conversion efficiency of about 4%.

Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

“…The bands observed at 1352 and 1473 cm À1 are assigned to the CeH swinging and bending of CH 2 group of the PEO respectively [36]. This results clearly indicated that the PEO is well blended with PVHF-HFP through a strong interaction between the CF 2 group of PVDFeHFP and CeOeC group of the PEO [31,32]. Whereas, the guanine incorporated PVDF-HFP/PEO/KI þ TBAI/I 2 blend electrolyte exhibited some of the vibrational bands at 1548, 1564, 1636, 1673, 1712, 3118 and 3321 cm À1 along with the above said bands (Fig.…”

“…As seen in Table 2, the values of T m, DH m and X c are found to be high for PVDF-HFP/KI þ TBAI/I 2 electrolyte and low in case of PVDF-HFP/PEO/KI þ TBAI/I 2 electrolyte. It indicates the decreased crystallinity of PVDF-HFP due to the addition of PEO [32]. Furthermore, the incorporation of guanine to the PVDF-HFP/PEO/ KI þ TBAI/I 2 electrolyte was also found to be largely reduce the crystallinity of the electrolyte.…”

“…These iodide ions may help to improve the ionic conductivity of the polymer electrolyte. Additionally, the amine (eNH 2 ) group of guanine may react with CeF group of PVDF-HFP through the formation of hydrogen bonds (FeH bonds) which will improve the compatibility between the guanine and the polymer, resulting in the decrease of the crystallinity of the polymer [32]. Therefore, a significant increase in the ionic conductivity of the guanine incorporated PVDF-HFP/PEO/KI þ TBAI/I 2 blend electrolyte could be due to the reduced crystallinity of the polymer and increased ionic mobility of the electrolytes [42].…”

“…The CF 2 group of the PVDFeHFP structure contributes a better compatibility while blending with PEO by means of strong interaction to CeOeC group which will considerably reduce the crystallinity of the PVDF-HFP [31]. Furthermore, the amine (eNH 2 ) group of guanine is expected to react with CeF groups of PVDF-HFP through the formation of hydrogen bonds by possibly forming FeH bonds that can enhance the compatibility between guanine and the polymers [32].…”

Structure and properties of polymer nanocomposite films with carbon nanotubes and graphene

“…In the electronic industry, electromagnetic interference (EMI) shielding is very important so carbonaceous nanofillers with their high electric conductivity, enhanced mechanical properties, low density, desired dielectric constant, and magnetic permeability render high EMI shielding efficiencies . Concerning optoelectronics, there is a wide range of applications which include, among others, fiber lasers , field emission devices , and photovoltaics , where the combination of tunable optoelectronic properties as well as structural and chemical stability, high surface area, and low mass density of nanofillers with the processability of polymers offers a new class of materials. Other energy conversion applications like wind power have found the use for PNCs as well, and since wind blade materials have to satisfy a number of criteria like low weight/density, high strength and fatigue resistance, high stiffness and excellent stability from environmental impacts, PNCs can ensure not only cost efficiency but extended working lifetimes as well .…”