Sensitive, High‐Speed, and Broadband Perovskite Photodetectors with Built‐In TiO2 Metalenses. Issue 41 (12th September 2021)

• Record Type: Journal Article
• Authors: Xiao, Ting; Zhao, Jie; Sun, Peng; Li, Peng; Zhang, Yaokang; Zhao, Ni; Ren, Zhiwei; Li, Gang; Huang, Zhifeng; Zheng, Zijian
• Is Part Of: Small. Volume 17:Issue 41(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-12
• Subjects: glancing angle deposition -- metalens -- perovskite -- photodetectors -- TiO 2; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202102694
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Monolithic integration of nanostructured metalenses with broadband light transmission and good charge transport can simultaneously enhance the sensitivity, speed, and efficiency of photodetectors. The realization of built‐in broadband metalenses in perovskite photodetectors, however, has been largely challenged by the limited choice of materials and the difficulty in nanofabrication. Here a new type of broadband‐transmitting built‐in TiO2 metalens (meta‐TiO2 ) is devised, which is readily fabricated by one‐step and lithograph‐free glancing angle deposition. The meta‐TiO2, which comprises of sub‐100 nm TiO2 nanopillars randomly spaced with a wide range of sub‐wavelength distances in 5–200 nm, shows high transmittance of light in the wavelength range of 400–800 nm. The meta‐TiO2 also serves as an efficient electron transporting layer to prevent the exciton recombination and facilitate the photoinduced electron extraction and transport. Replacing the conventional mesoporous TiO2 with the meta‐TiO2 comprehensively leads to enhancing the detection speed by three orders of magnitude to a few hundred nanoseconds, improving the responsivity and detectivity by one order of magnitude to 0.5 A W −1 and 10 13 Jones, respectively, and extending the linear dynamic range by 50% to 120 dB. Abstract : A new type of broadband‐transparent built‐in TiO2 metalens (meta‐TiO2 ) is readily fabricated by one‐step and lithograph‐free glancing angle deposition. The meta‐TiO2 comprehensively enhances the detection speed of photodetectors by three orders of magnitude and improves the detectivity.