Optical and Electrical Properties of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Perovskite Thin Films Transformed from PbO-PbI<sub>2</sub> Hybrid Films

Abstract

Organic-inorganic halide perovskites have been shown to be outstanding photovoltaic materials, achieving remarkably high power conversion efficiency (15%) of sunlight to electricity within the past 4 years. The controllable synthesis of organic-inorganic halide perovskites is fundamental to their applications in photovoltaic devices. Here we explore a novel strategy to prepare a typical halide peroskite CH3NH3PbI3 by transforming PbO-PbI2 hybrid materials. CH3NH3PbI3 thin films were deposited on glass substrates by reacting ultrasonic-assisted successive ionic layer adsorption and reaction (SILAR)-derived PbO-PbI2 hybrid films with CH3NH3I vapor at 110 °C. The microstructure and crystallinity of the films, together with the optical and electrical properties were characterized. Results show that CH3NH3PbI3 thin films possess perovskite crystal structure and uniform surface morphology with grain size up to 400 nm. In the visible band, CH3NH3PbI3 thin films showed low transmittance (below 10%), with a band gap of 1.58 eV. The surface resistivity of CH3NH3PbI3 thin films was as high as 1000 MΩ, indicating the dielectric nature of obtained CH3NH3PbI3 films, with a dielectric constant of er(100 Hz)=155 on low frequency. The current work opens an effective route toward high quality organic- inorganic halide perovskite films with good crystallinity and optical properties, which make them suitable for application in photovoltaic devices, and other optical and electrical applications.