1. Perovskite solar cells (PSCs) fabricated with two step deposition [1] have been prepared and tested using P3HT as hole transport layer (HTL). P3HT was dissolved in chlorobenzene and blended with single walled carbon nanotubes and graphene nanoplatelets bearing on the external surface covalently bound para-methoxyphenyl substituents (SWCNT-PhOMe and GNP-PhOMe respectively), aimed at improving their homogeneous mixing with the semiconducting polymer. Carbon nanostructures (CNSs) used for P3HT doping have been functionalized using aryl diazonium chemistry, keeping the amount of functionalities in a range which allows to gain better solubility in organic solvents but do not affect their electronic properties [2, 3]. Caution was taken in order to obtain blends with no insoluble CNSs residues, by applying a thorough protocol of sonication/centrifugation steps before spin coating the HTL on top of the hybrid junctions. Different weight percentages of functionalized CNSs with respect to P3HT were deposited, in order to determine the optimum percentage. Such doping of the P3HT layer resulted in increased efficiencies and prolonged stabilities of the resulting PSCs with respect to devices with un-doped P3HT HTLs. Indeed, the best solar cells showed a power conversion efficiency (PCE) up to 11.7 % and an improved stability with respect to PSCs based on un-doped P3HT [4]. [1] S. Casaluci et al,. “A Simple Approach for the Fabrication of Perovskite Solar Cells in Air”, Submitted. [2] J. M. Tour et al. Chem. Mater. 2001, 13, 3823-3824. [3] P. Salice et al., J. Mater. Chem. C 2015, 3, 303-312. [4] S. Casaluci, T. Gatti, A. Di Carlo, E. Menna, F. Bonaccorso “Perovskite solar cells stabilized by carbon nanostructure-P3HT blends” Proceedings of the 15th IEEE International Conference on Nanotechnology Rome, Italy, July 27-30, 2015. IMPROVED HOLE TRANSPORT LAYERS IN PEROVSKITE SOLAR CELLS BASED ON P3HT DOPED WITH CARBON NANOSTRUCTURES Simone Casaluci 1, Teresa Gatti 2, Aldo Di Carlo 1, Enzo Menna 2, Francesco Bonaccorso 3. 1 CHOSE – Center for Hybrid and Organic Solar Energy, Dipartimento di Ingegneria Elettronica, Università di Roma Tor Vergata, Roma, Italy 2 Organic Synthesis and Materials Research Group, Dipartimento di Scienze Chimiche, Università di Padova, Padova, Italy 3 Graphene Lab, Istituto Italiano di Tecnologia, Genova, Italy email: teresa.gatti@unipd.it THANKS TO : CNS FUNCTIONALIZATION: Centrifugation Sonication GNP-PhOMe Separation of supernatant Homogeneous P3HT/ SWCNT-PhOMe or GNP-PhOMe suspension P3HT in chlorobenzene Insoluble residue HTM To spin coater SWCNT-PhOMe / BLENDS PREPARATION: Perovskite Layer Pump Hot Plate Lid PbI 2 Solvent FTO Compact TiO 2 Hot Plate PbI 2 Annealing Perovskite Growth 1 st Step2 nd Step Meso- porous TiO 2 HTM Gold DEVICE FABRICATION: DEVICE CHARACTERIZATION: After fabrication, PSCs were kept in a glove box and after 15 hours were encapsulated with methacrylate glue and glass, then left in air. Best device with 4% GNP-PhOMe/P3HT blend We acknowledge PRIN project DSSCX (MIUR) and EU Graphene Flagship under contract n. 604391