title: Room-Temperature Solution-Processed NiOx:PbI2 Nanocomposite Structures for Realizing High-Performance Perovskite Photodetectors.
abstract: While methylammonium lead iodide (MAPbI3) with interesting properties, such as a direct band gap, high and well-balanced electron/hole mobilities, as well as long electron/hole diffusion length, is a potential candidate to become the light absorbers in photodetectors, the challenges for realizing efficient perovskite photodetectors are to suppress dark current, to increase linear dynamic range, and to achieve high specific detectivity and fast response speed. Here, we demonstrate NiOx:PbI2 nanocomposite structures, which can offer dual roles of functioning as an efficient hole extraction layer and favoring the formation of high-quality MAPbI3 to address these challenges. We introduce a room-temperature solution process to form the NiOx:PbI2 nanocomposite structures. The nanocomposite structures facilitate the growth of the compact and ordered MAPbI3 crystalline films, which is essential for efficient photodetectors. Furthermore, the nanocomposite structures work as an effective hole extraction layer, which provides a large electron injection barrier and favorable hole extraction as well as passivates the surface of the perovskite, leading to suppressed dark current and enhanced photocurrent. By optimizing the NiOx:PbI2 nanocomposite structures, a low dark current density of 2 × 10(-10) A/cm(2) at -200 mV and a large linear dynamic range of 112 dB are achieved. Meanwhile, a high responsivity in the visible spectral range of 450-750 nm, a large measured specific detectivity approaching 10(13) Jones, and a fast fall time of 168 ns are demonstrated. The high-performance perovskite photodetectors demonstrated here offer a promising candidate for low-cost and high-performance near-ultraviolet-visible photodetection.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam, Hong Kong, SAR China.
authors.forename: Hugh Lu
authors.initials: HL
authors.lastname: Zhu
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam, Hong Kong, SAR China.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam, Hong Kong, SAR China.|Department of Sustainable and Renewable Energy Engineering, University of Sharjah , Sharjah, United Arab Emirates.
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam, Hong Kong, SAR China.
authors.forename: Chunjun
authors.initials: C
authors.lastname: Liang
authors.affiliation: Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong , Kowloon, Hong Kong, SAR China.
authors.forename: Claas J
authors.initials: CJ
authors.lastname: Reckmeier
authors.affiliation: Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong , Kowloon, Hong Kong, SAR China.
authors.forename: He
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong , Kowloon, Hong Kong, SAR China.
authors.forename: Andrey L
authors.initials: AL
authors.lastname: Rogach
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pokfulam, Hong Kong, SAR China.
authors.forename: Wallace C H
authors.initials: WC
authors.lastname: Choy
keywords: high detectivity; low dark current; nanocomposite; perovskites; photovoltaic photodetectors