Manipulation of Shallow-Trap States in Halide Double Perovskite Enables Real-time Radiation Dosimetry

doi:10.21203/rs.3.rs-2477800/v1

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Manipulation of Shallow-Trap States in Halide Double Perovskite Enables Real-time Radiation Dosimetry

https://doi.org/10.21203/rs.3.rs-2477800/v1

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Storage phosphors displaying defect emission are indispensable in technologically advanced radiation dosimeters. The current dosimeter is limited to the passive detection mode, where ionizing radiation-induced deep-trap defects must be activated by external stimulations, such as ultraviolet light or heat. Herein, we designed a new type of shallow-trap storage phosphor by controlling the dopant amounts of Ag⁺ and Bi³⁺ in the host lattice of Cs₂NaInCl₆. A distinct phenomenon of X-ray-induced emission (XIE) is observed for the first time in an intrinsically nonemissive perovskite. The intensity of XIE exhibits a quantitative relationship with the accumulated dose, enabling a real-time radiation dosimeter. Thermoluminescence and in situ X-ray photoelectron spectroscopy verify that the emission originates from radiative recombination of electrons and holes associated with X-ray-induced traps. Theoretical calculations reveal the evolution process of Cl-Cl dimers serving as hole trap states. Analysis of temperature-dependent radioluminescence spectra provides evidence that the intrinsic electron-phonon interaction in 0.005Ag⁺@Cs₂NaInCl₆ is significantly reduced under X-ray irradiation. Moreover, 0.025Bi³⁺@Cs₂NaInCl₆ shows an elevated sensitivity to the accumulated dose with a broad response range from 0.08 Gy to 45.05 Gy. This work discloses defect manipulation in halide double perovskites, giving rise to distinct shallow-trap storage phosphors that bridge traditional deep-trap storage phosphors and scintillators and enabling a brand-new type of materials for real-time radiation dosimetry.

Physical sciences/Chemistry/Materials chemistry/Optical materials

Physical sciences/Chemistry/Inorganic chemistry/Solid-state chemistry

Storage phosphor is a type of luminescent material that has a function to record the radiation dose.^{1, 2, 3, 4} This type of material is extensively utilized for monitoring the ac-cumulated radiation dose in advanced radiation protection technologies, such as personal-, medical-, space- and security-dosimetry.^{5, 6, 7, 8} Contrasted with the scintillator, radiation-induced charge carriers are stored at defect states in the storage phosphor, forming metastable trapping centers.⁴ The radiation dose is generally proportional to the concentrations of trapped electrons and holes. Then, the trapped electrons and holes would be released through fluorescence emission under external optical/thermal stimulation, providing information on the recorded dose.² In most storage phosphors, oxygen and halogens are commonly used as chemical components because they can easily form various defects under irradiation. In addition, lanthanide dopants are widely used as trapping centers by adjusting the electronic structure of the host lattice. These material design criteria have created many dosimeter materials in the past several decades, i.e., Al₂O₃:C, CaF₂, CaSO₄:Dy and CaS:(Eu, Dy) et al.^{9, 10, 11, 12} However, one of the most significant unsolved issues is that the current dosimetry materials cannot assess radiation risk to individuals in real time. From the viewpoint of material design, controlling and manipulating defects are vital and promising for designing novel real-time radiation dosimeters.

Halide perovskites have recently received considerable attention due to their superior performances in solar cells,^{13, 14} light-emitting diodes,^{15, 16} photodetectors^{17, 18}, etc. In addition, combined with intrinsically high atomic constituents and decent optoelectronic properties, these emergent materials are recognized as promising candidates for next generation radiation detectors.^{19, 20, 21} In the past few years, halide perovskites have found substantial utilization in all fields of radiation detection spanning from X-ray imaging and gamma energy spectrum resolution to beta-particle detection.^{22, 23, 24, 25} The current mate-rials encompass both scintillators and semiconductors; however, they are rarely studied for storage phosphors. Halide perovskites have been proven to have outstanding advantages in designing storage phosphors. Intrinsic defects, including neutral (I_V), anionic (I_V⁺¹), and cationic (I_V^–1) iodine vacancies, are commonly observed in halide perovskites.²⁶ Furthermore, the high structural tolerance of perovskite provides a prerequisite for creating trapping states by doping additional activators, which shows great potential for developing novel radiation dosimeters.

In this work, for the first time, we designed a new type of shallow-trap storage phosphor by controlling the dopant amounts of Ag⁺ and Bi³⁺ in the host lattice of Cs₂NaInCl₆. Remarkably, unlike traditional storage phosphors and scintillators, these materials are intrinsically non-emissive but show continuously enhanced emission only under X-ray irradiation. In addition, the emission intensities of 0.005Ag⁺@Cs₂NaInCl₆ under X-ray irradiation exhibit a simultaneous quantitative relationship with the accumulated dose, enabling a new type of real-time radiation dosimeter. Thermoluminescence (TL) and in situ X-ray photoelectron spectroscopy (XPS) studies demonstrated that this type of emission originates from the radiative recombination of trapped electrons and holes within X-ray-induced trapping centers. Furthermore, the optimized compound of 0.025Bi³⁺@Cs₂NaInCl₆ shows a high detection sensitivity to accumulated dose with a broad response range from 0.08 Gy to 45.05 Gy.

Synthesis, structure and X-ray induced emissive properties of Ag⁺ doped Cs₂NaInCl₆

The crystals of Cs₂NaInCl₆ and Ag⁺-doped compounds are synthesized under hydrothermal methods through the combination of CsCl, NaCl, InCl₃ and AgCl with concentrated hydrochloric acid (detailed synthetic procedures can be found in the methods). Single crystal X-ray diffraction analysis demonstrates that Cs₂NaInCl₆ crystallizes in the \(Fm\stackrel{-}{3}m\) space group with an elpasolite lattice.²⁷ Fig. 1A shows that Cs₂NaInCl₆ displays a typical double perovskite structure where the dense three-dimensional structure is formed by corner-sharing [NaCl₆]^5– and [InCl₆]^3– octahedra, with Cs⁺ residing within the cavities. The pure phase is further confirmed by powder X-ray diffraction analysis (Figure S1). We initially investigated the optical properties of Cs₂NaInCl₆ under ultraviolet excitation. The direct electronic transitions from the conduction band minimum (CBM) and valence band maximum (VBM) in Cs₂NaInCl₆ are theoretically predicted to be parity-forbidden.²⁸ Therefore, the absorption peak from 210 nm to 260 nm originates from the electronic transition between the CBM and the lower level VBM (Figure S2A).²⁹ Featuring this electronic structure, Cs₂NaInCl₆ presents an intrinsically nonemissive feature at room temperature, consistent with recent reports in which a dark transition leads to undetectable luminescence.^{30, 31, 32} To explore the potential possibilities of storage phosphor in halide perovskite, we doped a trace amount of Ag⁺ in Cs₂NaInCl₆ (named 0.005Ag⁺@Cs₂NaInCl₆, where 0.005 is the feeding ratio) because Ag is often used to adjust trapping centers in other storage phosphor materials.^{33, 34} Similar to pure Cs₂NaInCl₆, 0.005Ag⁺@Cs₂NaInCl₆ maintains a nonemissive feature under UV excitation (Fig. 1B). Intriguingly, it exhibits a broad emission with a full width at half maximum of ∼0.7 eV under X-ray excitation, contrasting sharply with that excited by UV irradiation. The X-ray-induced emission in a nonemissive perovskite is unexpected. As demonstrated in recent works, the nonemissive feature of pure Cs₂NaInCl₆ is governed by strong electron-phonon interactions.^{30, 31} The X-ray-induced traps may significantly change the lattice vibrations of Ag⁺-doped Cs₂NaInCl₆, and we assume that this could change the electron-phonon interactions. We thus investigated the Huang-Rhys factor (S) of 0.005Ag⁺@Cs₂NaInCl₆ under X-ray irradiation. S is the number of phonons emitted with excited state relaxation after photoexcitation.^{35, 36, 37} The expression is S=∆E/ℏω, where ∆E is the relaxation energy of the excited states and ω is the frequency of the longitudinal optical (LO) phonon.^{35, 38} Recent theoretical works indicate that Cs₂NaInCl₆ has an intrinsically strong S of 80.31. Interestingly, under X-ray excitation, we clearly observe that the S of 0.005Ag⁺@Cs₂NaInCl₆ is reduced to 11.66 (Figure S3A and B), implying that the electron-phonon interactions are significantly reduced under X-ray irradiation. This observation demonstrates that X-ray result in a new relaxation process of excited states, and finally, the lattice is prone to be deformable under X-ray irradiation, which presents a high radiative transition probability, as shown in Figure S3C.

More remarkably, the emission intensity of the 0.005Ag⁺@Cs₂NaInCl₆ single crystal significantly increases as the X-ray irradiation dose increases. We further collected the emission spectrum with gradient radiation dosages. As shown in Fig. 1C, after being exposed to a radiation dose of 26.5 Gy, the emission intensity reaches saturation. Furthermore, we investigated the relationship between accumulated dose and emission intensity. As shown in Figure S2B, the emission of 0.005Ag⁺@ Cs₂NaInCl₆ exhibits nonlinear dependence on the accumulated dose. The luminescence intensity sharply increases under the initial X-ray irradiation and then reaches saturation with increasing dosage. In addition, the emission process can recycle constantly and maintain the stability of intensity, as shown in Fig. 1D. This X-ray-induced emission feature reveals that 0.005Ag⁺@ Cs₂NaInCl₆ can accumulate the received radiation dosage in real time. Moreover, we also synthesized other crystals of Cs₂NaInCl₆ with higher contents of Ag⁺. The powder X-ray diffraction (PXRD) data show that the different Ag⁺-doping ratio samples sustain the initial Cs₂NaInCl₆ structure. However, with increased Ag⁺ components, the absorption properties display obvious differences and are consistent with the reported results (Figure S2A).^{31, 32} Correspondingly, the emission properties are also different. For 0.025 and 0.05Ag⁺@Cs₂NaInCl₆, they are still nonemissive under UV excitation but possess luminescent processes similar to those of 0.005Ag⁺@ Cs₂NaInCl₆ under X-ray irradiation; the difference is the enhancement processes of emission intensity versus dose accumulation (Fig. 1F). In contrast, Cs₂Na_0.25Ag_0.75InCl₆ and Cs₂Na_0.5Ag_0.5InCl₆ are emissive under both UV and X-ray excitation (Fig. 1F and Table 1), which is attributed to the breakthrough of the parity-forbidden transition after large amounts of Ag⁺ doping and is consistent with the reported results.³¹ Moreover, they only have direct scintillating phenomena and no changes in intensity under persistent X-ray irradiation.

Table 1

Summary of the optical properties of Cs₂NaInCl₆ with different Ag⁺ and Bi³⁺ ion ratios.
Perovskites	Optical properties
Perovskites	UV excited emission feature	X-ray excited emission feature	RL enhanced with dose accumulation	Material classification
Cs₂NaInCl₆	X	X	X	None
0.005Ag⁺@ Cs₂NaInCl₆	X	√	√	Storage Phosphor
0.025Ag⁺@ Cs₂NaInCl₆	X	√	√	Storage Phosphor
0.05Ag⁺@ Cs₂NaInCl₆	X	√	√	Storage Phosphor
Cs₂Na_0.75Ag_0.25InCl₆	√	√	X	Scintillator
Cs₂Na_0.5Ag_0.5InCl₆	√	√	X	Scintillator
0.025Bi³⁺@ Cs₂NaInCl₆	X	√	√	Storage Phosphor
0.075Bi³⁺@ Cs₂NaInCl₆	X	√	√	Storage Phosphor
Cs₂NaIn_0.75Bi_0.25Cl₆	√	√	X	Scintillator
Cs₂NaIn_0.5Bi_0.5Cl₆	√	√	X	Scintillator
√ means the presence of emission. X means no emission.

The X-ray-induced trap formation mechanism.

In consideration of the proper emissive character of Ag⁺-doped Cs₂NaInCl₆, we speculated that the luminescence may originate from trap recombination induced by X-ray irradiation.^{39, 40} To understand the trap properties of Ag⁺-doped Cs₂NaInCl₆, we tested the thermoluminescence spectrum of 0.005Ag⁺@Cs₂NaInCl₆ under X-ray irradiation. Thermoluminescent measurement is widely used to verify the existence of traps that are generated by irradiation in storage phosphor materials.⁴¹ We initially froze the crystals at 213 K and then irradiated them with X-rays at different dosages. After cutting off the X-ray source, we found that the crystal displays significantly longer afterglow at 213 K compared with that at room temperature. The afterglow is directly related to the generation and concentration of traps. In addition, the afterglow time is also longer when higher X-ray doses are given (Figure S4). Until the spectrum of afterglow was almost undetectable at 213 K, thermoluminescence spectra began to be collected along increased temperature with a ramp-up rate of 0.17°C/s. As shown in Fig. 2A, compared to the case with no X-ray irradiation, significant thermoluminescence phenomena are observed under incremental irradiation dosages, which further demonstrates that the X-ray creates substantial traps within 0.005Ag⁺@Cs₂NaInCl₆. Furthermore, a broad band located at 248.5 K was recorded in the TL curves, implying that X-rays solely generate one type of trap state in 0.005Ag⁺@Cs₂NaInCl₆.42 In addition, Fig. 2B shows the integral area of the TL curve dependency on the received dosage, indicating that the trap concentration is highly correlated with the irradiated dosage. The above results directly illustrate that a new storage phosphor has been designed in the halide double perovskite Cs₂NaInCl₆. Based on the TL curves, we can roughly estimate the trap depth in 0.005Ag⁺@Cs₂NaInCl₆ from the equation E = T_m/500, where E is the trap depth in eV, and T_m is the transition point in the TL curve.^{43, 44} It should be noted that traditional storage phosphor materials usually have deep trap depths higher than 0.6 eV (Table S1), in which external optical/thermal stimulation is required to release the traps.^{9, 10, 11} However, a distinct trap depth of 0.50 eV is obtained for 0.005Ag⁺@Cs₂NaInCl₆. This shallow trap depth is inferred to make trapped electrons and holes spontaneously released at room temperature, leading to the dosage accumulation effect. In addition, the peak shape and position of the thermoluminescence and afterglow spectrum are identical to those of X-ray-induced emission, confirming that X-ray-induced emission of 0.005Ag⁺@Cs₂NaInCl₆ predominantly originates from the recombination of the same electron and hole traps. (Fig. 2C).

Different from UV light, X-rays have high enough energy to generate various point defects in bulk materials by ionization interactions, which can serve as electron or hole traps. According to the established theory of X-ray-matter interactions, Cl⁻ will be dislocated and form a well-known V_k center (Cl₂⁻) with another adjacent Cl⁻.^{4, 45} Cl₂⁻ is one of the typical hole trapping centers and has been widely explored in halide perovskites.^{41, 46} We thus inferred that Cl₂⁻ may play a critical role of hole trapping center in Ag⁺-doped Cs₂NaInCl₆. To explore the intrinsic trapping process of excited electrons and holes, we investigated the in situ XPS to reveal the X-ray-induced electron transfer behavior. Under continuous X-ray irradiation, the Cl 2p peaks notably shift to higher binding energies in both 0.05Ag⁺@Cs₂NaInCl₆ and pure Cs₂NaInCl₆, which means that electron-losing behavior appears in the Cl atom and indicates that hole-trapping centers (Cl₂⁻) are induced by X-ray excitation (Fig. 2D and S5C). However, the behavior of In 3d in 0.05Ag⁺@Cs₂NaInCl₆ is totally different from that in pure Cs₂NaInCl₆. As shown in Fig. 2D and S5A, not only a shift to lower binding energy but also two new shoulder peaks appear in In 3d₃ and 3d₅ at lower binding energy. This result indicates the electron-withdrawing character of In in Ag⁺-doped Cs₂NaInCl₆ under X-ray irradiation. In contrast, there is no obvious change in In 3d in pure Cs₂NaInCl₆ (Figure S5D). In addition, the microcomponent of Ag 3d also shows a detectable shift to lower binding energy in in situ XPS after irradiation (Figure S5B). These hints suggest that Ag⁺ doping promotes the formation of electron trapping centers in halide double perovskite Cs₂NaInCl₆ under X-ray irradiation. Moreover, density functional theory calculations were carried out to clarify the role of the Cl₂⁻ hole trapping centers induced by X-ray in Cs₂NaInCl₆ (detailed calculation methods can be found in the methods). Our calculation shows that two adjacent Cl atoms form a stable Cl₂⁰ dimer structure, with the Cl-Cl distance decreasing from 3.63 Å to 2.01 Å (Stage 1 in Fig. 3A). The trap state (red line in Figure S6A) appears in the band gap and serves as a hole trap mainly derived from the Cl-Cl anti-bonding orbitals. According to experimental observations, the traps can be released at room temperature, which is probably due to the destruction of the Cl₂⁰ dimer after trapping electrons. Therefore, we introduced an electron into Cl₂⁰-Cs₂NaInCl₆ to simulate the stability of the Cl₂⁻ dimer structure. As shown in Fig. 4A, the level of the Cl₂⁻ dimer (Stage 2) is 2.10 eV higher than that of the Cl₂⁰ dimer in total energy, implying that the Cl₂⁻ dimer can spontaneously recover. This state then relaxed into the low-lying energy state by phonon scattering (Stage 3, defined as L-Cl₂⁻). Finally, L-Cl₂⁻ fully relaxed to the initial state of Cs₂NaInCl₆ by capturing an electron (Stage 4). In addition, the calculation indicates that the relaxation of the Cl₂⁻ dimer is in a broad energy range due to multiple lattice vibrations. As shown in Figs. 3B and S6, the energy level of traps gradually decreased from 1.88 eV to 0.34 eV, accompanied by Cl-Cl distance relaxation to equilibrium status. The experimental value of 0.50 eV from TL measurements is right in the range. Overall, the in situ XPS and calculation results indicate that Cl₂⁻ serves as hole traps to capture holes under X-ray excitation in storage phosphor perovskite. At the same time, the trace doping ratio of Ag⁺ promotes the trapping of electrons in the In³⁺ site. Then, the spontaneous radiative recombination of trapped electrons and holes leads to X-ray-induced emission (Fig. 3C).

Regulating trap characteristics of Cs₂NaInCl₆ for improving detection sensitivity

The above results provide a new type of storage phosphor in Cs₂NaInCl₆ with a trace doping ratio of Ag⁺, and the continuously increased emission depending on the accumulated X-ray dose illustrates intrinsic real-time dosimetry. However, 0.005Ag⁺@Cs₂NaInCl₆ only works in a narrow dosage region, as shown in Fig. 1C. Since the X-ray-induced emission is associated with defect trap state formation, moreover, the In³⁺ site is the electron trapping center, we proposed that doping guest ions on this site would regulate the trap characteristics of Cs₂NaInCl₆. We thus incorporate the Bi³⁺ ions into the lattice that would sustain the structural integration of Cs₂NaInCl₆.²⁷ Here, we name the samples 0.025Bi³⁺@Cs₂NaInCl₆, 0.075Bi³⁺@Cs₂NaInCl₆, Cs₂NaIn_0.75Bi_0.25Cl₆, and Cs₂NaIn_0.5Bi_0.5Cl₆ based on different Bi³⁺ feeding ratios. The accurate amounts of Bi³⁺ and In³⁺ were confirmed by ICO-OES, as shown in Table S2, and the results are consistent with the increased Bi³⁺ feeding ratio. Clearly, four different samples maintain the initial structure (Figure S7) but exhibit distinctively different lattice vibrations (Figure S8). We investigated the optical properties of these samples under UV and X-ray irradiation. Similar to the Ag⁺-doped samples, only 0.025Bi³⁺@Cs₂NaInCl₆ and 0.075Bi³⁺@Cs₂NaInCl₆ with trace amounts of Bi³⁺ doping exhibit storage phosphor characteristics, as shown in Fig. 4A and S9. In contrast, the samples of Cs₂NaIn_0.75Bi_0.25Cl₆ and Cs₂NaIn_0.5Bi_0.5Cl₆ show distinct optical properties, manifesting direct UV excited emission and scintillating phenomena (Table 1 and Figures S9). The electronic transition spectra in Figure S10 indicate that a high doping ratio results in efficient electronic transfer between the [BiCl₆]³⁻ group and [InCl₆]³⁻ group and thus changes the electronic structure of Cs₂NaIn_0.75Bi_0.25Cl₆ and Cs₂NaIn_0.5Bi_0.5Cl₆. Intriguingly, unlike 0.005Ag⁺@Cs₂NaInCl₆, 0.025Bi³⁺@Cs₂NaInCl₆ has decent detection sensitivity with a dosage response range from 0.08 Gy to 45.05 Gy (Fig. 4A and Figure S11), which substantially covers technical demands in radiation detection fields. The in situ XPS analysis illustrates a similar trapping process of excited electrons and holes with 0.05Ag⁺@Cs₂NaInCl₆, as shown in Fig. 4B and 4C. In addition, the electron-lossing behavior in Bi 4f₇ shows that Bi may be involved in the hole-trapping process (Figure S12). We also measured the TL spectrum of 0.025Bi³⁺@Cs₂NaInCl₆ and calculated the trap depth as 0.51 eV, which is higher than that of 0.005Ag⁺@Cs₂NaInCl₆. (Table S1 and Figure S13). By fitting the data in Fig. 4A, we can quantitatively evaluate the emission intensity as a function of radiation dose from 1.33 Gy to 45.05 Gy (Fig. 4D). The equation Y = A·exp(-X/B) + C is then deduced, where A and C are constant parameters and B is a parameter associated with the dosage rate. Figure 4E shows the relationship between parameter B and the dosage rate. A linear dependence was obtained, indicating that 0.025Bi³⁺@Cs₂NaInCl₆ has the intrinsic property of dosage accumulation regardless of the variation in the dose rate. The above dose-dependent relationship suggests the application potential in real-time visualized radiation dosimetry. Furthermore, 0.025Bi³⁺@Cs₂NaInCl₆ exhibits a relatively long afterglow of more than 63 seconds (Fig. 4F), making it promising for applications such as radiation medical imaging.⁴⁷ In addition, the dynamic process of enhanced emission intensity and long afterglow are also recorded in the Supplementary Video.

In conclusion, we disclose a new type of storage phosphor in nonemissive halide double perovskite Cs₂NaInCl₆ by combining defect traps, which enables the development of real-time radiation dosimeters. Thermoluminescence and in situ XPS measurements and theoretical calculations indicate that trap formation and radiative recombination under X-ray irradiation result in this phenomenon. The depth of the shallow trap facilitates the spontaneous recombination of trapped electrons and holes at room temperature, leading to the dosage accumulation effect. In addition, we observe that the intrinsic electron-phonon interaction in 0.005Ag⁺@Cs₂NaInCl₆ is significantly reduced under X-ray irradiation. Finally, by regulating the trap characteristics of Cs₂NaInCl₆, we demonstrate that 0.025Bi³⁺@ Cs₂NaInCl₆ has a decent detection sensitivity with a dosage response range from 0.08 Gy to 45.05 Gy, which substantially covers technical demands in radiation monitoring fields. These findings not only provide a new horizon into the structure-property relationship of solids under irradiation with high-energy photons but also disclose a new attractive application for perovskite-based materials.

Materials

CsCl (99.999%, Strem Chemicals, Inc), NaCl (99.999%, Aladdin), InCl (99.995%, ThermoFisher Scientific), AgCl (99.5%, Aladdin), Bi(NO₃)₃·5H₂O (99.999%, ThermoFisher Scientific), and HCl (AR, 36 ~ 38%, Sinopharm Chemistry Reagent Co., Ltd) were used as received from commercial suppliers without further purification.

Synthesis

CsCl (0.4 mmol), 0.2 mmol NaCl and 0.2 mmol InCl₃ were mixed with 2 mL 12 M HCl and added into a 23 mL PTEF-lined autoclave to synthesize the pure phase of Cs₂NaInCl₆. AgCl (0.001 mmol, 0.005 mmol and 0.01 mmol) was added to the mixture for the synthesis of 0.005Ag⁺@Cs₂NaInCl₆, 0.025Ag⁺@Cs₂NaInCl₆ and 0.05Ag⁺@Cs₂NaInCl₆, respectively. In addition, Cs₂Na_0.75Ag_0.25InCl₆ and Cs₂Na_0.5Ag_0.5InCl₆ were synthesized by adding x mmol NaCl and 0.2-x mmol AgCl (x = 0.15, 0.1). The synthesis of Bi³⁺-doped samples is similar to that of Ag⁺-doped samples, except for choosing Bi(NO₃)₃·5H₂O as the raw material for Bi³⁺. All the mixtures were heated at 180°C for 12 h and cooled to room temperature at a rate of 3°C/h. Colorless crystals were obtained by washing them with ionized water and isopropanol.

Physical Property Measurements

Powder X-ray diffraction patterns were collected by using a Bruker D8 Advance X-ray diffractometer with Cu–Kα radiation (λ = 1.54056 Å). Raman spectroscopy, UV − vis absorption and photoluminescence (PL) spectrum data were measured on the single crystals using a Craic Technologies microspectrophotometer. X-ray excited radioluminescence (RL) and afterglow spectra were collected on an X-RAD SmART system equipped with a W-Kα radiation source (beam size of X-ray is 10×10 cm²) and a NOVA spectrometer (ideaoptics, China) with different dosage rates. The dosage rate was changed by adjusting the tube voltage and electricity. In addition, the accumulated doses were acquired by multiplying the dose rate and cumulative exposure time of the material under X-ray irradiation. The sizes of the single crystals chosen for RL-related measurements are both approximately 1×1×1 mm³. Temperature-dependent RL and thermoluminescence spectra were detected by coupling a Linkam Temperature Controlled Microscope Stage, as shown in Figure S14. Inductively coupled plasma optical emission spectrometer (ICP‒OES) analysis of separation was conducted using a Thermo Scientific ICAP 7400 instrument. X-ray photoelectron spectroscopy (XPS) spectra were collected with a Thermo escalab 250Xi (Al-Kα). For in situ measurements, we collected spectra every four minutes for three times with the continuous exposure of X-ray irradiation. Moreover, three spectra were collected at the same site.

Computational Method

Density functional theory calculations with the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE)⁴⁸ were carried out based on all-electron-like projector-augmented wave (PAW) potentials,⁴⁹ as implemented in the Vienna Ab initio Simulation Package (VASP).^{50, 51} Monkhorst-Pack k-point meshes⁵² of 7×7×7 were adopted for a (10.73 Å × 10.73 Å × 10.73 Å) supercell containing 40 atoms, and a plane-wave cut-off energy of 400 eV was used for the self-consistent calculations.

Calculation of the Huang–Rhys factors.

The Huang − Rhys factor (S) can be obtained by the following equation:

where FWHM is the full width at half maximum of temperature-dependent radioluminescence and ℏω_phonon is the phonon energy

Data availability. The data that support the findings of this paper are available in the paper and supplementary information files. Any further relevant data are available from the authors upon reasonable request. Source data are provided with this paper.

Acknowledgments. We are grateful for the funding support from the Natural Science Foundation of China (21825601, 22222606, 21790374) and the Natural Science Foundation of Jiangsu Province (BK20211546). The authors also thank beamlines BL14B1, BL19U1 and BL17B1 staff at the SSRF for providing the beamtime and User Experiment Assist System of SSRF for their help.

Author contributions. Y.X.W., S.W. and Z.C. conceived and supervised the project. Y.W., Y.W. and S.W. prepared the manuscript. Y.W., H.Q., L.Y., Z.Z. and M.Q. performed the experiments and analyzed the data. G.C. and W.Y. carried out the theoretical calculation. D.Z., Y.Y. and K.L. guided the experiments in Shanghai Synchrotron Radiation Facility.

Additional information. Supplementary information is available in the online version of the paper. Correspondence and requests for materials should be addressed to [email protected] (Shuao Wang), or [email protected] (Yaxing Wang).

Competing Financial Interests statement. All authors declare no competing financial interests.

Schweizer S. Physics and Current Understanding of X-Ray Storage Phosphors. Physica Status Solidi (a) 187, 335–393 (2001).
Yanagida T, et al. Ionizing-radiation-induced storage-luminescence for dosimetric applications. J. Lumin. 207, 14–21 (2019).
Yanagida T. Inorganic scintillating materials and scintillation detectors. Proc. Jpn. Acad. Ser. B. Phys. Biol. Sci. 94, 75–97 (2018).
Leblans P, et al. Storage Phosphors for Medical Imaging. Materials (Basel) 4, 1034–1086 (2011).
Heo SY, et al. Wireless, battery-free, flexible, miniaturized dosimeters monitor exposure to solar radiation and to light for phototherapy. Sci. Transl. Med. 10, (2018).
Lowder WM, Condon WJ. Measurement of the exposure of human populations to environmental radiation. Nature 206, 658–662 (1965).
Camanzi B, Holmes-Siedle AG. The race for new radiation monitors. Nat Mater 7, 343–345 (2008).
McDonald BA, et al. Low-density gel dosimeter for measurement of the electron return effect in an MR-linac. Phys. Med. Biol. 64, 205016 (2019).
Sarasola-Martin I, et al. Characterization of the red thermoluminescence emission of doped alumina: A case study for Al₂O₃:C and Al₂O₃:Cr,Ni. J. Alloys Compd. 886, 161262 (2021).
Rodríguez R, et al. Preliminary study on the thermoluminescence properties of CaF₂ and Tm₂O₃ pellets. Nucl. Instrum. Methods Phys. Res., Sect. A 959, 163561 (2020).
Lewandowski AC, Mathur VK. High Dose and Phototransferred Thermoluminescence in CaSO₄, CaSO₄:Dy, and CaSO₄:Tm. Radiat. Prot. Dosim. 66, 213–216 (1996).
Rodríguez Burbano DC, et al. Persistent and Photostimulated Red Emission in CaS:Eu²⁺,Dy³⁺ Nanophosphors. Advanced Optical Materials 3, 551–557 (2015).
Kojima A, et al. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J. Am. Chem. Soc. 131, 6050–6051 (2009).
Cao Q, et al. Efficient and stable inverted perovskite solar cells with very high fill factors via incorporation of star-shaped polymer. Sci Adv 7, (2021).
Yuan F, et al. Color-pure red light-emitting diodes based on two-dimensional lead-free perovskites. Sci Adv 6, (2020).
Xu W, et al. Rational molecular passivation for high-performance perovskite light-emitting diodes. Nature Photonics 13, 418–424 (2019).
Lin Q, et al. Filterless narrowband visible photodetectors. Nature Photonics 9, 687–694 (2015).
Fu Y, et al. Metal halide perovskite nanostructures for optoelectronic applications and the study of physical properties. Nature Reviews Materials 4, 169–188 (2019).
Kakavelakis G, et al. Metal Halide Perovskites for High-Energy Radiation Detection. Adv Sci (Weinh) 7, 2002098 (2020).
Zhou F, et al. Halide Perovskite, a Potential Scintillator for X-Ray Detection. Small Methods 4, 2000506 (2020).
Wei W, et al. Monolithic integration of hybrid perovskite single crystals with heterogenous substrate for highly sensitive X-ray imaging. Nature Photonics 11, 315–321 (2017).
Zhou Y, et al. Metal Halide Perovskites for X-ray Imaging Scintillators and Detectors. ACS Energy Letters 6, 739–768 (2021).
Chen Q, et al. All-inorganic perovskite nanocrystal scintillators. Nature 561, 88–93 (2018).
He Y, et al. Resolving the Energy of γ-Ray Photons with MAPbI₃ Single Crystals. ACS Photonics 5, 4132–4138 (2018).
Yu D, et al. Two-dimensional halide perovskite as beta-ray scintillator for nuclear radiation monitoring. Nat. Commun. 11, 3395 (2020).
Li W, et al. Control of Charge Recombination in Perovskites by Oxidation State of Halide Vacancy. J. Am. Chem. Soc. 140, 15753–15763 (2018).
Zhou J, et al. Manipulation of Bi³⁺/In³⁺ Transmutation and Mn²⁺-Doping Effect on the Structure and Optical Properties of Double Perovskite Cs₂NaBi_{1 – x}In_xCl₆. Advanced Optical Materials 7, 1801435 (2019).
Meng W, et al. Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites. J. Phys. Chem. Lett. 8, 2999–3007 (2017).
Liu X, et al. Tunable Dual-Emission in Monodispersed Sb³⁺/Mn²⁺ Codoped Cs₂NaInCl₆ Perovskite Nanocrystals through an Energy Transfer Process. Small 16, e2002547 (2020).
Zeng R, et al. Highly Efficient Blue Emission from Self-Trapped Excitons in Stable Sb³⁺-Doped Cs₂NaInCl₆ Double Perovskites. J. Phys. Chem. Lett. 11, 2053–2061 (2020).
Luo J, et al. Efficient and stable emission of warm-white light from lead-free halide double perovskites. Nature 563, 541–545 (2018).
Han P, et al. Lead-Free Sodium-Indium Double Perovskite Nanocrystals through Doping Silver Cations for Bright Yellow Emission. Angew. Chem. Int. Ed. 58, 17231–17235 (2019).
Zheng W, Kurobori T. Assignments and optical properties of X-ray-induced colour centres in blue and orange radiophotoluminescent silver-activated glasses. J. Lumin. 131, 36–40 (2011).
Kurobori T, et al. A comparative study of optical and radiative characteristics of X-ray-induced luminescent defects in Ag-doped glass and LiF thin films and their applications in 2-D imaging. Nucl. Instrum. Methods Phys. Res., Sect. B 326, 76–80 (2014).
Whalley LD, et al. Giant Huang-Rhys Factor for Electron Capture by the Iodine Intersitial in Perovskite Solar Cells. J. Am. Chem. Soc. 143, 9123–9128 (2021).
Andrews LJ, et al. Thermal quenching of chromium photoluminescence in ordered perovskites. I. Temperature dependence of spectra and lifetimes. Phys Rev B Condens Matter 34, 2735–2740 (1986).
McCall KM, et al. Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A₃M₂I₉ (A = Cs, Rb; M = Bi, Sb). Chem. Mater. 29, 4129–4145 (2017).
Wright AD, et al. Electron-phonon coupling in hybrid lead halide perovskites. Nat. Commun. 7, (2016).
Lao X, et al. Luminescence and thermal behaviors of free and trapped excitons in cesium lead halide perovskite nanosheets. Nanoscale 10, 9949–9956 (2018).
Wu X, et al. Trap states in lead iodide perovskites. J. Am. Chem. Soc. 137, 2089–2096 (2015).
Buryi M, et al. Trapping and Recombination Centers in Cesium Hafnium Chloride Single Crystals: EPR and TSL Study. J. Phys. Chem. C 123, 19402–19411 (2019).
Tang H, et al. High-Sensitivity and Wide-Linear-Range Thermoluminescence Dosimeter LiMgPO₄:Tm,Tb, for Detecting High-Dose Radiation. Inorg. Chem. 58, 9698–9705 (2019).
Shalgaonkar CS, Narlikar AV. Review: a review of the recent methods for determining trap depth from glow curves. J. Mater. Sci. 7, 1465–1471 (1972).
Cao Y, et al. Unraveling the Defect-Related Luminescence in a Eu²⁺-Doped Chlorosilicate Phosphor. J. Phys. Chem. Lett. 12, 958–965 (2021).
Momma K, Izumi F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. Crystallogr. 44, 1272–1276 (2011).
Tailor NK, et al. Observation of Negative Photoconductivity in Lead-Free Cs₃Bi₂Br₉ Perovskite Single Crystal. ACS Photonics 8, 2473–2480 (2021).
Ou X, et al. High-resolution X-ray luminescence extension imaging. Nature 590, 410–415 (2021).
Perdew JP, et al. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865 (1996).
Blöchl PE. Projector Augmented-wave method. Phys. Rev. B 50, 17953 (1994).
Kresse G, Furthmuller J. Efficiency of abinitio total energy calculations for metals and semiconductors using a plane-wave basis set. Comp. Mater. Sci. 6, 15–50 (1996).
Kresse G, Furthmüller J. Efficient iterative schemes for abinitio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996).
Monkhorst HJ, Pack JD. Special Points for Brillouin-zone Integrations. Phys. Rev. B 13, 5188 (1976).

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Manipulation of Shallow-Trap States in Halide Double Perovskite Enables Real-time Radiation Dosimetry

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Abstract

Figures

Introduction

Results

Synthesis, structure and X-ray induced emissive properties of Ag⁺ doped Cs₂NaInCl₆

Regulating trap characteristics of Cs₂NaInCl₆ for improving detection sensitivity

Discussion

Methods

Materials

Synthesis

Physical Property Measurements

Computational Method

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

Manipulation of Shallow-Trap States in Halide Double Perovskite Enables Real-time Radiation Dosimetry

Status:

Version 1

Abstract

Figures

Introduction

Results

Synthesis, structure and X-ray induced emissive properties of Ag+ doped Cs2NaInCl6

Regulating trap characteristics of Cs2NaInCl6 for improving detection sensitivity

Discussion

Methods

Materials

Synthesis

Physical Property Measurements

Computational Method

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

Synthesis, structure and X-ray induced emissive properties of Ag⁺ doped Cs₂NaInCl₆

Regulating trap characteristics of Cs₂NaInCl₆ for improving detection sensitivity