Improving the efficiency of polymer solar cells by incorporation of functionalized SWCNTs in organic photovoltaic cells based on P3HT:PCBM photoactive layer

The optical and electrical properties of bulk polymer RR-P3WI (regio-regular poly(3-hexylthiophene-2,5diyl):PCBM (methanofullerene phenyl-C₆₁-butyric-acid-methyl-ester) incorporated single walled carbon nanotubes (SWCNTs) have been already reported by a number of research groups. We investigated new approach to functionalize CarboLex single wall carbon nanotubes (SWCNTs-e) for increasing their dispersion on different solvent. The addition of SWCNTs-e in the matrix of P3HT:PCBM improve the photovoltaic (PV) characteristics. The results show that the photovoltaic parameters depend on the concentration of SWCNTs-e. The incorporation of low concentrations of SWCNTs-e in the photoactive layer increases the current density J_sc before annealing. We attribute the improved performance to partial crystallisation of the RR-P3WI. As revealed by XRD studies and confirmed by the absorbance spectra which exhibit the characteristic 600 nm shoulder. Interestingly, we observed also that doping the P3HT:PCBM system with the functionalized SWCNTs increases V_oc from 0.583 to 0.744 V.