Halide Perovskite: A Promising Candidate for Next-Generation X-Ray Detectors

Abstract

In the past decade, metal halide perovskite (HP) has become a superstar semiconductor material due to its great application potential in the photovoltaic and photoelectric fields. In fact, HP initially attracted worldwide attention because of its excellent photovoltaic efficiency. However, HP and its derivatives also show great promise in X-ray detection due to their strong X-ray absorption, high bulk resistivity, suitable optical bandgap, and compatibility with integrated circuits. In this review, the basic working principles and modes of both the direct-type and the indirect-type X-ray detectors are first summarized before discussing the applicability of HP for these two types of detection based on the pros and cons of different perovskites. Furthermore, the authors expand their view to different preparation methods developed for HP including single crystals and polycrystalline materials. Upon systematically analyzing their potential for X-ray detection and photoelectronic characteristics on the basis of different structures and dimensions (0D, 2D, and 3D), recent progress of HPs (mainly polycrystalline) applied to flexible X-ray detection are reviewed, and their practicability and feasibility are discussed. Finally, by reviewing the current research on HP-based X-ray detection, the challenges in this field are identified, and the main directions and prospects of future research are suggested.

Keywords: X-ray; detectors; halide; imaging; perovskites.

Figure 1

X‐ray detection application in different fields. Reproduced with permission.^{[ 8 ]} Copyright 2022, American Chemical Society.

Figure 2

Energy conversion and photoelectric processes of X‐ray detection. a) Interactions between X‐ray photons and semiconductor: photoelectric effect, Compton scattering, Rayleigh scattering, and electron–hole pair generation. Reproduced with permission.^{[ 9 ]} Copyright 2022, Elsevier. b) The detection mechanism of indirect‐type X‐ray detector. Reproduced with permission.^{[ 1 ]} Copyright 2021, Wiley‐VCH. c) The detection mechanism of direct‐type X‐ray detector. Reproduced with permission.^{[ 10 ]} Copyright 2021, American Chemical Society.

Figure 3

Operation mechanism of direct conversion X‐ray detectors. a) Current‐mode detector and b) pulse‐mode detector. Reproduced with permission.^{[ 15 ]} Copyright 2019, Springer Nature.

Figure 4

Electronic and optical properties of HPs. a) Linear attenuation coefficient of MAPbI₃, MAPbBr₃, CdTe, Se, and TlBr versus photon energy. b) The µτ product of MAPbBr₃ crystal devices with different feed ratios of raw materials and surface passivation procedures. Reproduced with permission.^{[ 15 ]} Copyright 2019, Springer Nature. c) Resistivity of Cs₂AgBiBr₆ and Cs₃Bi₂I₉ single crystals. (top) Reproduced with permission.^{[ 55 ]} Copyright 2017, Springer Nature. (bottom) Reproduced with permission.^{[ 56 ]} Copyright 2017, Springer Nature. d) The transition energy levels of intrinsic acceptors and intrinsic donors in MAPbI₃ perovskite. Reproduced with permission.^{[ 15 ]} Copyright 2019, Springer Nature.

Figure 5

Methods used for HP SC growth and the basic mechanisms of these methods. a) STL method. Reproduced with permission.^{[ 129 ]} Copyright 2015, Royalty Society of Chemistry. b) TSSG method and the SC obtained by this method. Reproduced with permission.^{[ 59 ]} Copyright 2015, AAAS. c) ITC method. Reproduced with permission.^{[ 130 ]} Copyright 2015, John Wiley and Sons. d) AVC method. Reproduced with permission.^{[ 132 ]} Copyright 2015, AAAS.

Figure 6

The deposition methods for forming diverse perovskite films. a) Sequential deposition by spin‐coating in two steps. Reproduced with permission.^{[ 135 ]} Copyright 2014, Springer Nature. b) Co‐evaporation deposition. Reproduced with permission.^{[ 139 ]} Copyright 2013, Springer Nature. c) Slot‐mold coating. Reproduced with permission.^{[ 141 ]} Copyright 2015, John Wiley and Sons. d) Spray‐coating deposition. Reproduced with permission.^{[ 142 ]} Copyright 2015, American Chemical Society. e) Doctor‐blade coating. Reproduced with permission.^{[ 8 ]} Copyright 2022, American Chemical Society. f) Vacuum flash‐assisted solution process. Reproduced with permission.^{[ 143 ]} Copyright 2016, AAAS.

Figure 7

Absorbance behaviors of HP materials as the ions of ABX₃ positioned at the A, B, and X sites are changed. a) The structure and absorption spectra of ABX₃ in which A can be inorganic (e.g., Cs⁺) or organic cations (e.g., MA⁺ and FA⁺). Reproduced with permission.^{[ 147 ]} Copyright 2017, Royalty Society of Chemistry. b) Photographs of mixed‐halide HP SCs incorporating I, Br, and Cl. c) UV–Vis–NIR absorption spectra of mixed‐halide HP SCs. Reproduced with permission.^{[ 148 ]} Copyright 2017, Springer Nature.

Figure 8

a) Schematic diagram of X‐ray‐induced luminescence in a lattice with a cubic all‐inorganic perovskite crystal structure. b) TEM micrograph of the prepared CsPbBr₃ nanocrystals. c) Tunable X‐ray‐induced luminescence spectra of the perovskite quantum dots (QDs). d) Optical sensitivity of perovskite QDs scintillators versus non‐perovskite scintillator materials under X‐ray illumination. e) Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of the X‐ray‐induced visible emissions measured for CsPbX₃ nanocrystals. f) Multicolor scintillation of nanocrystal scintillators induced by X‐rays. Reproduced with permission.^{[ 53 ]} Copyright 2018, Springer Nature.

Figure 9

a) MASnI₃ Reproduced with permission.^{[ 154 ]} Copyright 2016, John Wiley and Sons. b) FASnI₃ SCs obtained by optimizing crystal growth conditions. c) FASnCl₃ and d) FASnBr₃ SC. Reproduced with permission.^{[ 155 ]} Copyright 2016, American Chemical Society.

Figure 10

Schematic diagrams and the features of vertical and lateral architectures for direct‐type detection. a) Vertical devices with photodiode and photoconductor architectures; b) lateral devices with photoconductor and phototransistor architectures. Reproduced with permission.^{[ 158 ]} Copyright 2021, John Wiley and Sons.

Figure 11

Perovskite and metal electrode contact interface analysis. a) Energy levels of the well‐studied HPs, metals, and oxide electrodes. Reproduced with permission.^{[ 160 ]} Copyright 2022, John Wiley and Sons. b,c) Cross‐section schematics of metal electrodes on perovskite thin films made by thermal evaporated and van der Waals contact methods. d,e) The optical images, PL mapping, and line scan profiles of the PL mapping intensity for the samples in (c,d). Reproduced with permission.^{[ 161 ]} Copyright 2022, American Chemical Society.

Figure 12

a) Schematic diagram of MAPbI₃ detector with vertical structure. b) Photocurrent density as a function of X‐ray dose rate. c) Photograph (left) of a leaf and the corresponding X‐ray image (center) formed by the photoconductor along with photographs and X‐ray images of other samples. Reproduced with permission.^{[ 79 ]} Copyright 2015, Springer Nature. d) Illustration of a vertical structure for HP X‐ray detector. Reproduced with permission.^{[ 35 ]} Copyright 2015, Springer Nature. e) The X‐ray image of PI‐MAPbI₃ on a TFT backplane (α‐Si:H) by spin casting. f) X‐ray image of part of a smartphone observed in the digital detector. Reproduced with permission.^{[ 35 ]} Copyright 2017, Springer Nature.

Figure 13

a) The key device fabrication procedure via an inkjet printing method. b,c) Device response curves under X‐ray irradiation with various X‐ray dose rates or none at a given bias voltage of 0.1 V. d) X‐ray sensitivity and photocurrent curves at different dose rates at a given bias voltage of 0.1 V. e) Temporal response curves of a device with dose rates of 7.33 mGy_air s⁻¹ at a given bias voltage of 0.1 V. f) Device response curves at different bias voltages for X‐ray pulses with a dose rate of 7.33 mGy_air s⁻¹. Reproduced with permission.^{[ 6 ]} Copyright 2019, John Wiley and Sons.

Figure 14

a) Device structure of the MAPbBr₃ SC detector. b) Dynamic response curve to X‐rays in a MAPbBr₃ SC detector. Reproduced with permission.^{[ 71 ]} Copyright 2016, Springer Nature. c) Device structure of the Si‐integrated MAPbBr₃ SC detector. d) Dose rate dependent X‐ray‐generated photocurrent of the Si‐integrated MAPbBr₃ SC detector. Reproduced with permission.^{[ 70 ]} Copyright 2017, Springer Nature. e) SNR of the Cs₂AgBiBr₆ SC X‐ray detector at different applied voltage. f) Sensitivity of the Cs₂AgBiBr₆ SC X‐ray detector. Reproduced with permission.^{[ 55 ]} Copyright 2017, Springer Nature. g,h) Device structures of the MAPbI₃ based X‐ray detectors with the type I symmetric electrode and type II asymmetric electrode. i) Dark I–V curves of the detector with symmetric and asymmetric structure. Reproduced with permission.^{[ 91 ]} Copyright 2019, John Wiley and Sons.

Figure 15

Schematic illumination of two types of FAMACs SC X‐ray detectors with different electrode configurations: a) symmetric type with Au electrodes at both sides and b) asymmetric type with SpiroTTB/Au and C60/BCP/Au serving as hole and electron collection electrodes. c,d) Energy levels and corresponding band diagrams of the two types of devices. e,f) J–V curves of the two kinds of X‐ray detectors under dark conditions. g) The relationship between the X‐ray sensitivity of the SC X‐ray detectors and the bias voltage. h) The current response of the SC X‐ray detectors. i) The long‐term stability of the SC detectors. Reproduced with permission.^{[ 89 ]} Copyright 2021, John Wiley and Sons.

Figure 16

2D Perovskite SC X‐ray detector with vertical structure. a,b) Pictures and corresponding XRD of the 2D (PEA)₂PbI₄ SC and (F‐PEA)₂PbI₄ SC, respectively. c,d) The crystal structure of 2D (PEA)₂PbI₄ and (F‐PEA)₂PbI₄, respectively. e) Device structure of the 2D (PEA)₂PbI₄ SC and (F‐PEA)₂PbI₄ SC detector. f) Bulk resistivity determination of the 2D (PEA)₂PbI₄ SC and (F‐PEA)₂PbI₄ SC detector. g) Detection limit of the 2D (F‐PEA)₂PbI₄ SC X‐ray detector. h) Stability of the 2D (F‐PEA)₂PbI₄ SC X‐ray detector. Reproduced with permission.^{[ 40 ]} Copyright 2020, John Wiley and Sons.

Figure 17

1D Perovskite SC X‐ray detector with vertical structure. a) Crystal structures of the 1D (DMEDA)BiI₅. b) Device structure of the (DMEDA)BiI₅ SC detector. c) X‐ray response current of the (DMEDA)BiI₅ SC detector under different dose rate and bised at 300 V voltage. d) Dose rate dependent response current density of the (DMEDA)BiI₅ SC detector for various bias voltages. e) Sensitivity of the (DMEDA)BiI₅ SC detector at different biases. Reproduced with permission.^{[ 114 ]} Copyright 2020, Royalty Society of Chemistry.

Figure 18

X‐ray detectors with lead‐free HP SC. a) Schematic diagram of a vertical‐type detector with 0D MA₃Bi₂I₉ SC. b) Dynamic response to X‐rays in SC MA₃Bi₂I₉. c) The relation curves of X‐ray response current with irradiation dose rates at different voltages (the slope of each fitting line represents the sensitivity). d) The optical sensitivity of SC MA₃Bi₂I₉ under various given applied electric fields. e) Gain factor of a MA₃Bi₂I₉ SC detector for various X‐ray dose rates under different electric fields. f) I–t curves of photocurrent response of the MA₃Bi₂I₉ under various X‐ray dose rates and electric fields. Calculated signal‐to‐noise ratios are given. Reproduced with permission.^{[ 57 ]} Copyright 2020, Elsevier. g) Comparison of photocurrent densities of anisotropic (NH₄)₃Bi₂I₉ SC at different X‐ray dose rates and electric field orientations. Solid lines represent pristine conditions and dotted lines are after 60 days ageing under ambient conditions. h) Sensitivities of (NH₄)₃Bi₂I₉ SC to X‐rays. i) Signal‐to‐noise ratio of (NH₄)₃Bi₂I₉ devices with the electric field parallel and perpendicular to the 001 facet. Reproduced with permission.^{[ 106 ]} Copyright 2019, Springer Nature.

Figure 19

The response of an HP SC coplanar detector under X‐ray illumination. a) Schematic diagram of the coplanar‐structured detector and the corresponding electric field distribution in the device. b) Photoconductivity response of the (BDA)PbI₄ SC. Reproduced with permission.^{[ 166 ]} Copyright 2022, Royalty Society of Chemistry. c) The carrier transport in MA₃Bi₂I₉ SC along different directions parallel or perpendicular to the inorganic layer. d) Response current under different X‐ray dose rates and different bias voltages. e) Response current curve of the MA₃Bi₂I₉ co‐planar X‐ray detector under various X‐ray dose rates and 100‐V bias voltage. f) Transient response curve of the MA₃Bi₂I₉ SC coplanar detector under X‐ray illumination. Reproduced with permission.^{[ 116 ]} Copyright 2020, John Wiley and Sons.

Figure 20

Perovskite heterojunction and corresponding detector devices. a) Schematic illustration of the 3D perovskite heterojunction of Cs_0.15FA_0.85PbI₃ and Cs_0.15FA_0.85Pb(I_0.15Br_0.85)₃. b) The current response of the heterojunction device to the chopped 40‐keV X‐ray source with variable dose rates under an electric bias of ‐25 V. c) X‐ray images of the UNC logo obtained by the heterojunction detector under different X‐ray fluxes. Reproduced with permission.^{[ 90 ]} Copyright 2021, AAAS. d) Photograph of the (BA)₂CsAgBiBr₇/Cs₂AgBiBr₆ heterocrystal. e) I–V curves of the heterocrystal device measured in the dark. f) I–V curves of the heterocrystal device under different light intensities of a 405‐nm laser. Reproduced with permission.^{[ 5 ]} Copyright 2021, American Chemical Society. g) Photograph of a FAPbBr₃ SC. h) Photograph of a FAPbBr₃/(FPEA)₂PbBr₄ 3D/2D heterojunction SC. i) Current density dependence on X‐ray dose rate of the SC detectors. Reproduced with permission.^{[ 169 ]} Copyright 2021, John Wiley and Sons.

Figure 21

Schematic diagrams of imaging modes and features of three different kinds of X‐ray imaging processes: a) single pixel detection, b) 1D detector array scanning, c) 2D detector arrays coupled with DAC timer scanning. The different characteristics (pros and cons) of the three different imaging processes are listed below them. Reproduced with permission.^{[ 15 ]} Copyright 2019, Springer Nature.

Figure 22

Single‐pixel HP X‐ray detector for imaging. a) Optical images and corresponding X‐ray images of a leaf, a Kinder egg and an electronic key card with a chip and integrated radio‐frequency antenna. Reproduced with permission.^{[ 79 ]} Copyright 2019, Springer Nature. b) Optical image (top) and X‐ray image (bottom) of a stainless‐steel plate that has lines etched through, a spring inside a capsule, a part of a fish fin and an “N”. Reproduced with permission.^{[ 70 ]} Copyright 2017, Springer Nature. c) Schematic illustration of single‐pixel detector scanning‐mode X‐ray imaging. The X‐ray images of objects with different shapes and thicknesses obtained using the MA₃Bi₂I₉ SC coplanar X‐ray detector. d) a 1 mm‐thick metal gasket, a 5 mm‐thick nut, a 2 mm‐thick wrench and a key with a junction between the metal part and opaque rubber. Insets: the corresponding photographs of the objects. Reproduced with permission.^{[ 57 ]} Copyright 2020, Elsevier.

Figure 23

Linear‐array HP X‐ray detectors for imaging. a) Schematic illustration of the X‐ray imaging device with Si‐integrated MAPbBr₃ SC as the active material of X‐ray detectors. b) X‐ray image of an “N” detected using the 1D linear detector array. Reproduced with permission.^{[ 70 ]} Copyright 2021, John Wiley and Sons. c) Optical image and X‐ray image of a heart‐shaped object obtained using the BiOBr‐passivated Cs₂AgBiBr₆ wafer linear X‐ray detector array. Reproduced with permission.^{[ 104 ]} Copyright 2019, Springer Nature. d) Photograph and enlarged view, and e) spatial resolution of the MAPbI₃ SC‐based coplanar X‐ray detector linear array. Reproduced with permission.^{[ 167 ]} Copyright 2021, John Wiley and Sons.

Figure 24

The application of perovskite materials in the FPD imaging configuration. a) Schematic illustration of a direct FPD with a thick semiconductor layer as the charge generation layer and pixel TFT array and top electrode for charge collection, which have been summarized in the cross‐sectional device structure. b) The X‐ray image of a hand phantom obtained by a Pe‐FPD. c) The estimated thickness for various perovskite materials to absorb 98% of the flux of 10–100 keV X‐rays. Reproduced with permission.^{[ 8 ]} Copyright 2022, American Chemical Society.

Figure 25

The properties of CsPbX3 NCs‐based X‐ray scintillation materials: a) Summary of the optical sensitivity of various scintillator materials under exposure to X‐rays. b) CIE chromaticity coordinates of the X‐ray‐induced visible emissions of samples 1–12. c) The dose rate‐dependent radioluminescence intensity of a CsPbBr₃ scintillator. The detection limit to X‐rays of 13 nGy s⁻¹ is estimated from the slope of the fitting line, with a signal‐to‐noise ratio of 3. d) Schematic illustration of the experimental setup for real‐time X‐ray imaging. A beetle is used as the object, which was mounted onto a plate between the scintillation film and X‐ray source. E) Bright‐field picture and f) the 50‐keV X‐ray‐induced picture under dark conditions of the sample, which were obtained with a camera. Reproduced with permission.^{[ 53 ]} Copyright 2018, Springer Nature.

Figure 26

a) Schematic diagram of the CsPbBr₃ nanocrystal sensitizing the perylene dyad. b) Waveguiding tests on CsPbBr₃ nanocrystal‐sensitized plastic scintillators. Reproduced with permission.^{[ 50 ]} Copyright 2020, Springer Nature. c) Photographs of CsPbBr₃ nanocrystals, PPO, and colloidal hybrid CsPbBr₃ nanocrystals +PPO in octane under illumination with white and UV light. d) Schematic illustration of the radiation luminescence of the PPO hybridized CsPbA₃ NC and CsPbA₃ NC. e) Optical and X‐ray images of an electric power plug and a crab. Reproduced with permission.^{[ 179 ]} Copyright 2020, Springer Nature.

Figure 27

a) Illustration of the emitter‐in‐matrix CsPbBr₃@Cs4PbBr₆ structure. b) Large‐area CsPbBr₃@Cs₄PbBr₆ film. c) Photograph and X‐ray image of a capsule containing a spring. Reproduced with permission.^{[ 178 ]} Copyright 2020, American Chemical Society. d) Mechanisms of two types of charge‐transport paths in hybrid devices. e) Photograph of a hybrid detector array. f) Photograph and X‐ray image of a pen nib. Reproduced with permission.^{[ 183 ]} Copyright 2022, John Wiley and Sons.

Figure 28

HP SCs with the structure change from 3D to 2D to 1D and to 0D for X‐ray detection. a) Pictures of 3D Cs₂Ag_0.6Na_0.4In_0.85Bi_0.15Cl₆ SCs under daylight and UV light excitation. b) Pictures and SEM images of the Cs₂Ag_0.6Na_0.4In_0.85Bi_0.15Cl₆ polycrystalline wafer. c) Picture and X‐ray image of a circuit board. Reproduced with permission.^{[ 186 ]} Copyright 2020, Springer Nature. d) Picture of a 2D (C₆H₅CH₂CH₂NH₃)₂PbBr₄ SC. Reproduced with permission.^{[ 189 ]} Copyright 2017, Springer Nature. e) Pictures of a 2D (EDBE)PbCl₄ SC under day light and ultraviolet lamp excitation. Reproduced with permission.^{[ 16 ]} Copyright 2016, Springer Nature. f) Picture of a 1D CsCu₂I₃ SC. g) Pictures, photoluminescent and SEM image of the 1D CsCu₂I₃ polycrystalline thin film, the X‐ray imaging also inserted. Reproduced with permission.^{[ 205 ]} Copyright 2021, American Chemical Society. h) Picture of the 0D Cs₄PbBr_6‐xCl_x SCs. i) The X‐ray imaging based on the Cs₄PbBr_{6‐ x} Cl _x SCs. Reproduced with permission.^{[ 192 ]} Copyright 2021, American Chemical Society.

Figure 29

Flexible HP direct‐type X‐ray detectors. a) Illustration of the flexible CsPbBr₃ QD X‐ray detector. b) Photograph of the CsPbBr₃ QD X‐ray detector. c) I–V curves of the detector arrays when bending at different angles. d) I—V curves of the flexible detector arrays after bending for 20, 50, 100, and 200 cycles. Reproduced with permission.^{[ 6 ]} Copyright 2019, John Wiley and Sons.

Figure 30

Flexible HP direct‐type X‐ray detectors. a) Schematic diagram of the perovskite‐filled nylon membrane. b) Photographs of a flexible nylon membrane with area of 400 cm². c) Photoconductivity of the MAPbI₃ and MAPb(I_0.9Cl_0.1)₃PFM device. d) Comparison of the measured X‐ray detection sensitivity of flexible X‐ray detectors. Reproduced with permission.^{[ 85 ]} Copyright 2020, Springer Nature. e) X‐ray detector architecture and layer stack. f) X‐ray response of flexible triple‐cation perovskite thin‐film X‐ray detector. Reproduced with permission.^{[ 86 ]} Copyright 2020, American Chemical Society. g) Sensitivity of the Au/Cs₄PbI₆/Au detector after bending for 600 cycles at an angle of 90°. h) X‐ray response sensitivity versus the storage time in air. Reproduced with permission.^{[ 121 ]} Copyright 2021, American Chemical Society. i) Schematic of a 2‐terminal X‐ray detector fabricated on PET substrate. Reproduced with permission.^{[ 219 ]} Copyright 2022, John Wiley and Sons. j) Sketches of Cs₂TeI₆ detector structures based on flexible substrate. k) J–V curves of the flexible detector after bending for different numbers of cycles. l) Xray current density dependence on the X‐ray dose rate. m) X‐ray images of an M6 nut and a copper leaf using the Cs₂TeI₆ film detector. Reproduced with permission.^{[ 122 ]} Copyright 2021, American Chemical Society.

Figure 31

Flexible HP indirect‐type X‐ray detectors. a) Photograph of the CsPbBr₃@PMMA films under the illumination of UV light. b) The modulation transfer function (MTF) of CsPbBr₃@PMMA films with different thickness (0.01, 0.04, 0.09, 0.15 mm). c) X‐ray images obtained from the CsPbBr₃@PMMA films. Reproduced with permission.^{[ 220 ]} Copyright 2022, John Wiley and Sons. d) Photograph of the CsPbBr₃ polymer‐ceramics. e) The MTF of the CsPbBr₃ polymer‐ceramics. f) X‐ray images and photograph of the standard X‐ray resolution pattern plate and the encapsulated spring. Reproduced with permission.^{[ 206 ]} Copyright 2022, John Wiley and Sons.

Figure 32

Flexible Cu‐base HP indirect‐type X‐ray detectors. a) The Cs₃Cu₂I₅‐polydimethylsiloxane film (CCI‐P) under UV excitation: bending, twisting, and folding. b,c) X‐ray images of the flexible copper grid obtained using a 50‐µm CCI‐P film. d) MTF of the Cs₃Cu₂I₅‐polydimethylsiloxane film. Reproduced with permission.^{[ 204 ]} Copyright 2022, American Chemical Society.