Preparation and transport properties of hybrid organic-inorganic CH3NH3SnBr3 films

We describe the preparation, structural and transport properties of CH3NH3SnBr3 organic-inorganic hybrid films (500 nm thick), which crystallize as cubic perovskites. They were deposited by single source thermal ablation technique, in a 10(-6) mbar vacuum chamber on glass, polymeric and crystalline substrates. X-ray diffraction proved that they were well crystallized and c-axis oriented. Resistivity measurements as a function of temperature showed a semiconductor behaviour. The activation energy, Delta E, was estimated by fitting the linear portions of the resistivity vs. temperature plots and was found to be (0.30 +/- 0.01) eV in the 260-230 K temperature interval. A significant change in resistivity was observed at a low temperature T=225 K in coincidence with the structural distortion in the Sn-Br-Sn chains. A field effect device was used to determine the charge carrier type and mobility as a function of temperature and field. The charge carriers were hole type. Their mobility at room temperature was about 10(-5) cm(2)V(-) s(-1). It increased by two orders of magnitude at 320 K and exhibited an almost exponential dependence on the applied gate voltage.