A universal strategy toward two-component organic-inorganic metal halide luminescent glasses and glass-crystal composites

Abstract

The development of melt-quenched organic-inorganic metal halide (OIMH) glasses is hampered by the scarcity of suitable organic molten salts and low luminescence efficiency. Herein, we developed a series of two-component OIMH amorphous glasses consisting of (TPG)₂MnBr₄ (TPG⁺, triphenylguanidium) and A₂MnBr₄ (A, organic molten cation), named α_G(A_xTPG_y). The high glass-formation ability (GFA) in (TPG)₂MnBr₄ provides a platform to modulate the crystallization of another molten A₂MnBr₄ by homogeneous melting. Moreover, the GFA modulation allows controlled in situ crystallization of α_G(A_xTPG_y) and the formation of transparent glass-crystal composites with higher luminescence efficiency. For instance, the light yield of α_G(PTP₉₉TPG₁) (PTP⁺, propyltriphenylphosphonium) is improved from 18,800 to 35,140 photons per mega-electron volt after annealing at 55°C, showing huge application potentials in radiation detection and high-resolution x-ray imaging. The present research would inspire further exploration of high-performance OIMH glasses and facilitate multiple applications in advanced photonics such as scintillators, photoconductive fibers, light-emitting diodes, and laser crystals.

Fig. 1.. Structural, thermodynamic, and photophysical properties of (TPG)₂MnBr₄ crystal and glass.

(A) The single crystal structure of (TPG)₂MnBr₄. (B) TGA and DSC plots of (TPG)₂MnBr₄ crystal. Inset images are photographs of (TPG)₂MnBr₄ crystal and glass under natural light and ultraviolet light excitation. (C) PXRD patterns of (TPG)₂MnBr₄ crystal and glass and the simulated one derived from SCXRD result. (D) T_g/T_m ratios of (TPG)₂MnBr₄ and other reported Mn-based OIMH glasses [P₄₄₄₄⁺, tetrahexylphosphonium; MTP⁺, methyltriphenylphosphonium; ETP⁺, ethyltriphenylphosphonium; BuTP⁺, (n-butyl)triphenylphosphonium; HTPP⁺, hexyltriphenylphosphonium; BTP⁺, benzyltriphenylphosphonium; DPG⁺, N,N′-diphenylguanidinium; DOTG⁺, 1,3-di-o-tolylguanidine]. (E) Fitting Fourier-transformed EXAFS spectra at Mn K-edge of (TPG)₂MnBr₄ crystal and glass. (F) PLE and PL spectra of (TPG)₂MnBr₄ crystal and glass. a.u., arbitrary units.

Fig. 2.. Preparation, structure, and thermodynamics of single-component and two-component OIMH glass.

(A) T_d and T_m values of single-component A₂MnBr₄ materials. (B) Preparation process and photographs for two-component OIMH glasses. (C) PXRD patterns of two-component OIMH glasses. (D) The second up-scan heating DSC curves of two-component OIMH glasses.

Fig. 3.. Thermodynamic, rheological, and structural analysis of two-component OIMH glasses.

(A) T_g/T_m ratios of A₂MnBr₄ and α_G(A₁TPG₁). (B) Viscosities and flow activation energies of A₂MnBr₄ and α_G(A₁TPG₁). (C) Fitting Fourier-transformed Mn K-edge EXAFS spectra of α_G(PTP₁TPG₁) glass. (D) PDFs for two-component α_G(PTP₁TPG₁) and α_G(PTP₉TPG₁) glasses.

Fig. 4.. In situ crystallization and scintillation properties of α_G–C(PTP_xTPG_y).

(A) The T_g values of α_G(PTP_xTPG_y) versus the mass ratio of parent materials. (B) Schematic diagram of the in situ crystallization process. (C) Light transmittance spectra of annealed α_G–C(PTP_xTPG_y) with varying x:y ratios. (D) PXRD patterns of α_G–C(PTP_xTPG_y). (E) Light yields of α_G(PTP_xTPG_y) and α_G–C(PTP_xTPG_y). (F) Fitting signal-to-noise ratio (SNR) of α_G–C(PTP_xTPG_y) under low-dose-rate irradiation.

Fig. 5.. Scintillation application of α_G–C(PTP_xTPG_y).

(A) Schematic representation of the home-built x-ray imaging system, the target subject was placed between the x-ray source and shading film. (B) X-ray images of a chip using α_G–C(PTP_xTPG_y) with varying x:y ratios (total dose of one image is 0.4 mGy). (C) Gray value contours along the lines of the red box extracted from Fig. 4B. (D) Spatial resolution of the α_G–C(PTP₉₉TPG₁) determined by a lead-made line pair card. (E) Gray value contours extracted from Fig. 4D. (F) Dynamic x-ray images of rotating lead fan blade using the α_G–C(PTP₉₉TPG₁) (total dose of one image is 22.6 μGy).

Fig. 6.. Mechanical properties.

(A) Load-displacement curves recorded in five parallel tests. (B) Young’s modulus (E) as a function of indentation depth for (TPG)₂MnBr₄ glass, α_G (PTP₉₉TPG₁), and annealed α_G–C(PTP₉₉TPG₁). (C) The summary of E and H values for polymers, OIMH glasses, ZIF glasses, inorganic glasses, and metallic glasses.