Effect of Modulating Spin-Coating Rate of TiO2Precursor for Mesoporous Layer onJ-VHysteresis of Solar Cells with Polar CH3NH3PbI3Perovskite Thin Film

Abstract

Compared with the crystalline Si solar cells, theJ-Vcharacteristics of CH3NH3PbI3perovskite solar cells are different under forward and reverse scan, and the CH3NH3PbI3film exhibits some polarization properties. To explore those performances of the mesoporous TiO2layer based perovskite solar cells, we focus on the effect of modulating the spin-coating rate of the TiO2precursor for mesoporous layer onJ-Vhysteresis of solar cells with the polar film byJ-Vcurves, atomic force microscopy topographic images, and piezoresponse force microscopy phase images. Firstly, the AFM images illustrate that the polarization behaviors exist and the deformation scale is large at the corresponding position when the DC bias voltage increases. Secondly, it is suggested that the polar films which applied the positive DC biases voltage show a tendency to 0° phase angle, while the polar films which applied the negative DC biases voltage show a tendency to −180° phase angle. Thirdly, a weak polar hysteresis loop relation for CH3NH3PbI3film was observed. Finally, the hysteresis index for the 1500 rpm mesostructured solar cell shows relatively lowJ-Vhysteresis compared with the 3000 rpm mesostructured and the planar-structured solar cell. Our experimental results bring novel routes for reducing the hysteresis and investigating the polar nature for CH3NH3PbI3material.