Interface band structure engineering by ferroelectric polarization in perovskite solar cells

We demonstrate the presence of ferroelectric domains in CH(3)NH(3)Pb1(3) by piezoresponse force microscopy and quantify the coercive field to the switching of the polarization of ferroelectric CH(3)NH(3)Pb1(3). For CH(3)NH(3)Pb1(3) perovskite solar cell, negative electric poling decreases the net built-in electric field, driving potential and width of depletion region inside the absorber layer, which hinders charge separation and deteriorates photovoltaic performance; while positive poling boosts these electrostatic parameters and therefore improves the charge separation inside the absorber. Low coercive field (8 kV/cm) enables the switching of CH(3)NH(3)Pb1(3) polarization during the current density-voltage (J-V) measurement. Forward scan initially activates the negative poling, whereas reverse scan first activates the positive poling, which can lead to the J-V hysteretic behavior. Comparative analysis with a traditional ferroelectric 0.25BaTiO(3)-0.75BiFeO(3) solar cell is conducted to confirm the impact of ferroelectric polarization and J-V scanning direction on photovoltaic performance. (C) 2015 Elsevier Ltd. All rights reserved.