研究目的
To demonstrate the potential of the 0-D “all-inorganic” perovskite material Cs2TeI6 as a sensitive all-inorganic X-ray photoconductor for the development of the new generation of direct photon-to-current conversion flat panel X-Ray imagers.
研究成果
The air-stable, all-inorganic and lead-free material 0-D halide perovskite Cs2TeI6 can be deposited as active thick films for flat panel X-ray imagers. Highly quality all-inorganic Cs2TeI6 thick films can be obtained by E-spray deposition processing in air, with the substrate temperature of ~160 °C, using a DMF and ethanol (1:1) mixture as the solvent, an optimized electrical bias and nozzle to substrate distance of 15 kV and 7.5 cm, respectively. The resulting Cs2TeI6 thick films exhibit high resistivity of 4.2×1010 Ω·cm. The Cs2TeI6 multilayer device is fabricated and shows a promising photoresponse to the optical light, with an on-off ratio of 15 under the ambient light (~0.8 mW·cm-2). The X-ray sensitivity achieved by Cs2TeI6 thick film device is already comparable to those of established flat panel X-ray detectors, with a sensitivity of 192 nC·R-1cm-2 under relative low electrical field.
研究不足
The study does not discuss the long-term stability of the Cs2TeI6 films under continuous X-ray exposure or the scalability of the E-spray deposition method for industrial production.
1：Experimental Design and Method Selection:
The study employed an electrostatic assisted spray (E-spray) deposition method to grow thick Cs2TeI6 film under atmospheric conditions. The E-spray coating process allows large area, reproducible and uniform fabrication of high-quality thin films.
2：Sample Selection and Data Sources:
Cs2TeI6 solutions with the concentrations range of 5-30 mg·mL-1 were prepared by dissolving CsI and TeI4 into the mixed solvent with the molar ratio of 2:
3：List of Experimental Equipment and Materials:
A stainless steel needle with an inter diameter of
4：06 mm was used. The spraying rate was controlled by a syringe pump at a range of 0-5 mL·h-An electric field of 12-17 kV was applied by a DC power supply between a metal orifice and the fluorine-doped tin oxide (FTO) substrate. Experimental Procedures and Operational Workflow:
The Cs2TeI6 solutions were loaded into a plastic syringe. The spraying rate was controlled by a syringe pump. An electric field was applied by a DC power supply between a metal orifice and the FTO substrate. The distance from nozzle to FTO substrate was in the range of 4-10 cm. During the E-spraying deposition, the substrate temperature was kept at the range of 110-175 °C. The thickness of Cs2TeI6 layers were controlled by the E-spraying duration time.
5：Data Analysis Methods:
The electrical properties of a 25-μm-thick Cs2TeI6 device were characterized at room temperature. A resistivity of 4.2×1010 Ω·cm for the Cs2TeI6 thick films was obtained by fitting the current-voltage (I-V) curve.
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