Single walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) covalently and non-covalently functionalised by zinc phthalocyanine (ZnPc) were added to P3HT:PCBM blend in order to investigate the effects of these hybrid materials on P3HT:PCBM organic solar cell performance. Adding a small amount of these hybrids to P3HT:PCBM blend does not significantly alter the absorption spectra of the latter nor its structure. ZnPc–rGO and ZnPc–SWCNT hybrid features have appeared on the P3HT:PCBM surface morphology as verified by SEM and AFM images. However these hybrid materials have caused significant effects on the electrical properties of the studied blends. An increase of about two orders of magnitudes has been observed in the electrical conductivity. Space charge limited conduction theory was employed to investigate the charge carriers' mobility whereas a thermionic emission model was used to evaluate the recombination rate based on an estimated diode ideality factor. Solar cell devices based on P3HT:PCBM:ZnPc–SWCNTs-co bonded have demonstrated best device performance with PCE of 5.3%, J_sc of 12.6 mA cm⁻², V_oc of 0.62 V and FF of 68%. A reference device based on bare P3HT:PCBM blend has exhibited PCE of just under 3.5%, J_sc of 9.3 mA cm⁻², V_oc of 0.62 V and FF of 60%.

The synthesis and characterization of new hybrid materials based on reduced graphene oxide (rGO) or single walled carbon nanotubes (SWCNTs) covalently functionalized by 4,4′-difluoro-8-(4-propynyloxy)-phenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY) (2) or 7-(prop-2-yn-1-yloxy)-3-(3′,4′,5′-trimethoxyphenyl)-coumarin (4) as light harvesting groups have been described. The organic solar cell performances of these novel nanomaterials in P3HT:PCBM blends were investigated. These covalently bonded hybrid materials (reduced graphene oxide:BODIPY (GB), reduced graphene oxide:Coumarin (GC), SWCNTs:BODIPY (CB) and SWCNTs:Coumarin (CC)) were prepared by an azide–alkyne Huisgen cycloaddition (click) reaction between the azide bearing SWCNTs or rGO and terminal ethynyl functionalized BODIPY (2) or coumarin (4) derivatives. The formation of novel nanomaterials was confirmed by FT-IR, UV-Vis and Raman spectroscopies and thermogravimetric analysis. The best performance on P3HT:PCBM organic solar cells was produced by SWCNTs:Coumarin (CC) hybrids which were coated on an indium tin oxide coated polyethylene terephthalate film (ITO-PET). The reference device based on the P3HT:PCBM blend without CC showed a power conversion efficiency (PCE) of 1.16%, an FF of 35% and a short-circuit current density (J_sc) of 5.51 mA cm⁻². The reference device with CC hybrids within the P3HT:PCBM blend increased the values significantly to 1.62% for PCE, 40% for FF and 6.8 mA cm⁻² for J_sc.