Single walled carbon nanotubes based hybrid solar cell

In this work, the excellent optical and electrical properties of (6, 5) single walled carbon nanotubes (SWNTs) have been exploited towards the fabrication of a hybrid solar cell where the SWNTs thin film works both as light-absorber layer and hole-transporting layer, while TiO2 is used as electron-transporting compound. We started from commercial HiPco carbon nanotubes, which have been used only for simple tests in the design of the solar cell, then we demonstrate the device operation employing highly purified PFO-BPy wrapped (6, 5) carbon nanotubes films in the optimized structure. In order to increase the effective interface area for carbon nanotube’s exciton dissociation into free charges, different oxide morphologies have been tested, i.e. compact, mesoporous and tree-like nanostructured thin films. On the other hand, in order to address the issue of the electronic coupling at the hybrid interface, solar cells made with a TiO2 surface functionalized by a monolayer of the molecule [6,6]-phenyl-C61-butyric acid (PCBA) were fabricated. The characterization of the solar cells under simulated sun light (AM1.5) reveals that the tree-like nanostructured TiO2 films are the best solution, enhancing the density of active photovoltaic interfaces. The solar cell with the PCBA functionalized tree-like TiO2 substrate delivered the best performances, showing an open circuit voltage of 0.38V, a short circuit current density of 0.36mA/cm2, a fill factor of 21.9% and an overall power conversion efficiency of 0.0376%.