两步互扩散法制备高性能CsPbCl_(3)薄膜紫外光电探测器

UV Photodetectors Based on High Quality CsPbCl_(3) Film Prepared by a Two-Step Diffusion Method

紫外光电探测器无论在军用和民用上都有着巨大的应用前景,CsPbCl_(3)作为钙钛矿家族中形成能最大,化学性能稳定的成员,在可见光盲区的紫外光电探测器中有着很大潜在的应用价值。本文针对CsPbCl_(3)薄膜难以制备的问题,发展了一种两步互扩散溶液法,通过控制前驱体PbCl2的形貌,成功地制备了CsPbCl_(3)薄膜。利用扫描电镜、吸收光谱和X射线表征技术,证实了制备出的薄膜表面平整无孔洞、晶粒饱满和吸光度强。通过瞬态荧光和变激发光强的稳态荧光,揭示了薄膜具有载流子寿命长、缺陷态少等优异性能。最终构建出了响应度为0.75 A·W^(−1)的横向结构紫外光电探测器,为将来进一步发展高性能CsPbCl_(3)薄膜紫外光电探测器奠定了基础。

Visible-blind ultra-violet(UV)photodetectors have great application prospects in military and civilian fields.Hence,it is important to develop highefficiency UV photodetectors.Perovskite materials have been widely applied in many fields,such as solar cells,light-emitting diodes,and photodetectors,owing to their excellent optical properties.The CsPbCl_(3) perovskite has a great potential in visible-blind UV photodetectors owing to its stable chemical properties and a suitable band gap.However,due to the extremely poor precursor solubility of CsPbCl_(3),it is difficult to find a suitable solvent to prepare CsPbCl_(3) films.In this study,we developed a two-step diffusion method to prepare CsPbCl_(3) films.PbCl2 and CsCl were dissolved in different solvents to overcome the solubility problem of CsPbCl_(3).First,the PbCl2 film was spin coated on a soda-lime glass.The CsCl solution was then continually dropwise spin-coated on the PbCl2 film to form the CsPbCl_(3) film.By controlling the morphology of PbCl2 through different annealing temperatures,the influence of different PbCl2 precursor films on microstructure of the CsPbCl_(3) film was investigated.The X-ray diffraction and scanning electron microscopy profiles of the PbCl2 precursor film and the CsPbCl_(3) film suggested that when the annealing temperature was too low,excess dimethyl sulfoxide(DMSO)remained in the PbCl2 precursor film,which hindered the transformation of CsPbCl_(3).However,when the annealing temperature was too high,voids appeared in the CsPbCl_(3) film due to excess DMSO volatilization,which caused pinholes in the CsPbCl_(3) film.Finally,a pinhole-free,smooth CsPbCl_(3) film with full grains was obtained when PbCl2 was annealed at 80°C.To the best of our knowledge,this is the first time a high-quality CsPbCl_(3) film with 1μm grains was prepared using a two-step diffusion method.Photoelectrical characterizations,such as ultravioletvisible absorption,steady-state photoluminescence(PL),and time-resolved PL characterizations,were studied to evaluate the quality of the film.The as-prepared CsPbCl_(3) film had strong UV absorption and PL intensity,and its longer PL lifetime indicated that the film had fewer defect states.Furthermore,a UV photodetector with a lateral structure based on the CsPbCl_(3) film was fabricated.The related electrical characterizations,such as current voltage curves,showed a good responsivity of 0.75 A·W^(−1) and an outstanding detectivity of 7.8×10^(12)Jones,which are better than those of contemporary commercial photodetectors.The findings of this study show that a two-step diffusion method can be used to prepare CsPbCl_(3) films with better features and that it has a great potential in the development of UV photodetectors in the future.