PbO-PbI2复合物膜转化的CH3NH3PbI3钙钛矿薄膜及其光电特性

有机-无机卤化物钙钛矿是一类优异的光电材料. 在过去四年内, 基于有机-无机卤化物钙钛矿的光电器件实现了超过15%的光电转换效率. 而有机-无机卤化物钙钛矿材料的可控制备是保证其在光电器件中应用的基础. 本文采用新的沉积方法在玻璃衬底表面制备了一种典型的有机-无机卤化物钙钛矿CH₃NH₃PbI₃薄膜. 其制备过程是: 采用超声辅助的连续离子吸附与反应法在玻璃衬底表面沉积PbO-PbI₂复合物膜, 之后与CH3NH3I蒸汽在110 ℃环境下反应, 将PbO-PbI₂复合物膜转化成CH₃NH₃PbI₃钙钛矿薄膜. 对CH₃NH₃PbI₃薄膜的微观结构, 结晶性及其光电性能等进行了表征. 结果表明, CH₃NH₃PbI₃薄膜呈晶态, 具有典型的钙钛矿晶体结构. 薄膜表面形貌均匀, 晶粒尺寸超过400 nm. 在可见光范围, CH₃NH₃PbI₃薄膜透过率低于10%, 能带宽度为1.58eV. 电学性能研究表明CH₃NH₃PbI₃薄膜表面电阻率高达1000 MΩ. 高表面电阻率表明CH₃NH₃PbI₃薄膜具有一定的介电性能, 其介电常数(ε_r)在100 Hz时达到155. 本研究提出了一种制备高质量CH₃NH₃PbI₃钙钛矿薄膜的新方法, 所得CH₃NH₃PbI₃薄膜可望在光、电及光电器件中得到应用.

Optical and Electrical Properties of CH3NH3PbI3 Perovskite Thin Films Transformed from PbO-PbI2 Hybrid Films

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 ℃. 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 ε_r(100 Hz)=155 on low frequency. The current work opens an effective route toward high quality organicinorganic halide perovskite films with good crystallinity and optical properties, which make them suitable for application in photovoltaic devices, and other optical and electrical applications.