Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV16)
Publication date: 28th March 2016
In this work CH3NH3PbI3 perovskite films were prepared through several modifications of the one-step solution deposition method and the consequences in crystallisation and morphology were investigated. Perovskites were synthesized in both N-Methyl-2-pyrrolidone (NMP) and N,N-Dimethylformamide (DMF) solvents and deposited by spin-coating at speeds between 2000 rpm and 7000 rpm. Intense evaporation process and solvent extraction methods based respectively on dry air blowing and toluene/chlorobenzene additions during film formation were also evaluated. Results indicate that solvent selection for perovskite solution has a strong influence on the primary shape of the crystals obtaining needle-like films with DMF meanwhile round-crystals grow with NMP. Spin-coating speed affects nucleation rate and favours film densification but full coverage and very low roughness films require additional rapid solvent elimination techniques. Perovskites were characterized by atomic force microscopy, scanning electron microscopy, X-ray diffraction and UV-vis spectroscopy. Selected conditions were used to fabricate planar solar cells on FTO substrates with Spiro-MeOTAD as the hole transport material. Current density-voltage curves under simulated solar irradiation evidenced strong differences among the studied devices.