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. 2021 Nov 3;2(1):108-113.
doi: 10.1016/j.fmre.2021.10.004. eCollection 2022 Jan.

Template directed perovskite X-ray detectors towards low ionic migration and low interpixel cross talking

Menghua Zhu  1   2 , Xinyuan Du  1 , Guangda Niu  1 , Weiwei Liu  1 , Weicheng Pan  1 , Jincong Pang  1 , Wenyu Wang  1 , Chao Chen  1 , Yadong Xu  2 , Jiang Tang  1
Affiliations

Template directed perovskite X-ray detectors towards low ionic migration and low interpixel cross talking

Menghua Zhu et al. Fundam Res. .

Abstract

The metal halide perovskites exhibit excellent performance as the direct X-ray detectors owing to their strong absorption capability, long carrier lifetime and diffusion length, radiation ruggedness, etc. For imaging applications, the ionic migration of perovskites and charge sharing effect between the adjacent pixels have a significantly negative impact on the spatial resolution. Herein, for the first time, the porous anodic aluminum oxides (AAO) have been used as a template to grow the CsPbBr2I thick film for the direct X-ray detection. Benefiting from the oxygen passivation effect, the activation energy for ionic migration has been observed to increase to 0.701 eV, whereas the dark current drift (1.01 × 10-5 nA cm-1s-1V-1) is one to two orders of magnitude lower than the other lead halide perovskite single crystals and films. Moreover, the AAO insulating wall effectively blocks the charge diffusion effect across a pixel pitch of 10 μm. Overall, the findings reported in this study open a new route for reducing the ionic migration and pixel crosstalk, thus, bringing the perovskite X-ray detectors close to the practical applications.

Keywords: Aluminum oxides (AAO); Crosstalk; Perovskite; X-ray detection.

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Conflict of interest statement

The authors declare that they have no conflicts of interest in this work.

Figures

Image, graphical abstract
Graphical abstract
Fig 1
Fig. 1
The fabrication and characterization of the columnar structured perovskite films. (a) The schematic illustration of the hot-press process. (b,c) Top-down SEM images of the pristine AAO template (b) and CsPbBr2I-AAO film (c), while the insets present the cross-sectional images. (d) XRD patterns of the fabricated CsPbBr2I-AAO film, and the inset presents the crystal structure.
Fig 2
Fig. 2
The characterization of the ionic migration in the perovskite film. (a) The recorded dark current drift of the films. The pure CsPbBr2I film was biased at an electric field of 0.91 V μm−1, whereas the CsPbBr2I-AAO film was biased at 3.64 V μm−1 (the dark current drift is calculated as per the published data as (Ifinish-Ibegin)/(t × s × E), where Ibegin and Ifinish are the recorded initial and final dark current values after a certain interval time (t), s is the pixel area, and E is the applied electric field). (b) Temperature-dependent conductivity of the CsPbBr2I films with and without AAO. (c) The Pb 4f XPS spectra of the films.
Fig 3
Fig. 3
The X-ray detection performance. (a) The attenuation efficiency of different semiconductors at an X-ray photon energy value of 50 keV. (b) Device response to the X-ray photons as a function of the dosing rates. (c) X-ray photocurrent versus dosing rates under different electric fields. (d) The device sensitivity as a function of the electric field.
Fig 4
Fig. 4
(a) The influence of the primary electron-hole pairs, K(L) fluorescence and charge diffusion on the charge sharing effect. (b,c) Schematic illustration of the directed migration and diffusion of the charge cloud in the presence and absence of the AAO template. (d) The recorded current of a given pixel is under the influence of the neighboring pixel. (e) The optical (top) and X-ray (down) images of the logo were obtained by the CsPbBr2I/AAO detector.
See this image and copyright information in PMC

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