TiO2 electron transport bilayer for all-inorganic perovskite photodetectors with remarkably improved UV stability toward imaging applications. (10th June 2021)

• Record Type: Journal Article
• Authors: Yuan, Ye; Ji, Zhong; Yan, Genghua; Li, Zhuowei; Li, Jinliang; Kuang, Min; Jiang, Bangqi; Zeng, Longlong; Pan, Likun; Mai, Wenjie
• Is Part Of: Journal of materials science & technology. Volume 75(2021)
• Page Start: 39
• Page End: 47
• Publication Date: 2021-06-10
• Subjects: TiO2 bilayer film -- All-Iinorganic perovskite -- Photodetector -- UV stability -- Atomic-layer-deposition -- Reflective imaging; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2020.10.028
• Languages: English
• ISSNs: 1005-0302

Abstract

Abstract: High ultraviolet (UV) stability and low dark current ( Idark ) are necessary for high-quality perovskite photodetectors (PDs). TiO2 thin film is known as effective electron-transport-layer (ETL) for perovskite devices. However, common spin-coated TiO2 ETLs endow many surface defects and have strong UV photocatalytic effect to decompose perovskite materials, resulting in inferior stability of devices. In this work, TiO2 bilayer film (Bi-TiO2 ) has been fabricated by combining spin-coating and atomic-layer-deposition process and its positive effects on UV stability and Idark of Cs2 AgBiBr6 -based PDs have been revealed for the first time. It is demonstrated that Bi-TiO2 possesses fewer surface defects and smoother morphology with type Ⅱ band alignment, which is beneficial to suppress photocatalytic activity of TiO2 and reduce carrier recombination at the interface. After accelerated strong UV aging treatment, the PD with Bi-TiO2 maintains excellent performance, whereas the PD with spin-coated TiO2 film dramatically deteriorate with on-off ratio drops from ∼10 2 to ∼2. Besides, the Idark of PD remarkably decreases from ∼10 −8 A to ∼10 −10 A after bilayer optimization. Furthermore, we have integrated the corresponding PDs into a self-built imaging system adopting diffuse reflection mode. This work suggests a feasible approach to fabricate TiO2 /Cs2 AgBiBr6 -based PDs with remarkable UV tolerance for imaging applications.