Fabrication Of High-Quality CH₃NH₃PbI_3-xCl_x Films And Investigation On The Photoelectric Properties

As active material for optoelectronic devices,the CH₃NH₃PbI_3-xCl_x film has longer carrier diffusion length and high mobility and has been widely concerned in the field of optoelectronic devices.In this work,we choose CH₃NH₃PbI_3-xCl_x as our subject and a solvent-assisted thermal-pressure strategy is developed to achieve the secondary growth of perovskite grains in the films and fabricated high-quality CH₃NH₃PbI_3-xCl_x Films.We investigated the effects of different factors on the microstructure and crystallinity of the films and explored the optoelectronic properties of the films.The results are as follows:（1）We investigated the influence of pressure on sample stability using an in-situ Fourier transformation infrared spectrometer and found that the decomposition temperature of CH₃NH₃PbI₃-xCl,was significantly improved under high pressure.This characteristic provides a guarantee for the second growth of perovskite grains under hot pressure conditions.（2）We fabricate the CH₃NH₃PbI_3-xCl_x perovskite thin films using pressure-assisted space-confined strategy and explored the effects of temperature,pressure,cooling time and holding time on the quality of the film and the properties of the optoelectronic devices.The study found that the grain size of the film obviously increased using pressure-assisted space-confined strategy.Compared to the perovskite optoelectronic devices using conventionally annealed strategy,the optoelectronic properties of the photocurrent,on/off ratio,sensibility have been greatly improved.（3）We fabricate high-quality CH₃NH₃PbI_3-xCl_x solvent-assisted thermal-pressure strategy.The film has large-sized grains（5-10μm）,high orientation and smooth,low defect density,good crystallinity and long carrier lifetime and so on.And we explored the effects of temperature,pressure,cooling time and holding time on the quality of the film and the properties of the optoelectronic devices.We optimized experimental conditions and fabricated high-quality perovskite thin films.As a consequence,the photodetectors based on the high-quality CH3NH3Pbl（3-x）Cl_x films exhibit enhanced photoelectrical performance:high on/off ratio（>2.1×104）,fast response time（54/63 μs）,and high detectivity（～1.3×1012）.