Abstract
In this paper, we studied the influence of polyvinylpyrrolidone (PVP) as a stabilization additive on optical and electrical properties of perovskite formamidinium lead iodide (FAPI) polycrystalline thin films on ZnO nanorods (ZNR). FAPI (as an active layer) was deposited from a single solution on ZNR (low temperature processed electron transport layer) using a one-step method with the inclusion of an anti-solvent. The role of PVP in the formation of the active layer was investigated by scanning electron microscopy and contact angle measurements to observe the effect on morphology, while X-ray diffraction was used as a method to study the stability of the film in an ambient environment. The effect of the PVP additive on the optical and electrical properties of the perovskite thin films was studied via photoluminescence, UV-Vis measurements, and electrical impedance spectroscopy. We have demonstrated that PVP inclusion in solution-processed perovskite FAPI thin films prevents the degradation of the film in an ambient atmosphere after aging for 2 months. The inclusion of the PVP also improves the infiltration of FAPI perovskite into ZnO nanostructures, increases electrical conductivity and radiative recombination of the photo-generated charge carriers. These results show promising information for promoting PVP stabilized FAPI perovskites for the new generation of photovoltaic devices.
Highlights
After the first report of a unique photoactive material based on lead halide compounds by Kojima et al [1], a whole new field of scientific research regarding inorganic-organic lead halide perovskites (LHP) emerged
Once we have confirmed the structural stability of the material, we have examined the optical properties of the perovskite with and without the PVP additive, as well as their variability in a given time period
ZnO nanostructures were prepared in the form of ZnO nanorods, as an appropriate candidate for low temperature processed electron transport layer in perovskite photovoltaic devices
Summary
After the first report of a unique photoactive material based on lead halide compounds by Kojima et al [1], a whole new field of scientific research regarding inorganic-organic lead halide perovskites (LHP) emerged. FAPbI3 , usually referred to as FAPI, perovskite bandgap gives a measured value of 1.43 eV [4], which is closer to the ideal bandgap value according to the Shockley–Queisser limit curve [5] than the value of measured MAPbI3 counterpart of 1.51 eV. FA-based perovskites have an unstable phase structure: under ambient and humid atmosphere the perovskite cubic α-FAPI transforms into the undesirable non-perovskite yellow δ-FAPI polymorph [6]. In order to improve the phase stability of the cubic α-FAPI, researchers have attempted various approaches: doping
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