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High-precision nondestructive evaluation of a thermal barrier coating based on perovskite quantum dot anion exchange
Nano Research 2024, 17 (5): 4582-4592
Published: 12 January 2024
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Thermal barrier coatings (TBCs) in gas turbine engines are used in expressly harsh environments; thus, assessing TBC integrity status is critical for safety and reliability. However, traditional periodic maintenance involves visual inspections of the TBCs, requiring the gas turbine to be decommissioned and partially dismantled. Most importantly, tiny defects or internal damages that easily cause coating failure cannot be identified. In this work, a new nondestructive evaluation (NDE) technique of TBCs based on quantum dot (QD) anion exchange is first explored internationally. By exchanging anions between the Cl ions and the CsPbBr3 QDs, the degrees of salt corrosion of the TBCs are evaluated. The resultant NDE technique shows that the colour of the TBCs obviously changes from green to blue, accompanied by a large blueshift (~ 100 nm) of the photoluminescence (PL) peak position. In addition, the relationship between the PL peak position and coating thermophysical properties indicates that the precision of this NDE technique may easily identify the μm-level of the thermal growth oxide (TGO) changes inside the TBCs.

Open Access Research paper Issue
Lateral organic-inorganic hybrid Vis-NIR photodetectors based on GaN nanowires promoting photogenerated carriers transfer
Journal of Materiomics 2022, 8 (4): 806-814
Published: 02 February 2022

The narrow bandgap of the low-energy near-infrared (NIR) polymer would lead to overlap between adjacent energy levels, which is a major barrier to the preparation of Vis-NIR polymer bulk heterojunction (BHJ) photodetectors with small responsivity and photocurrent. In this study, a high-performance lateral inorganic-organic hybrid photodetector was constructed to eliminate this barrier by combining GaN nanowires (GaN-NWs) with PDPP3T: PC61BM-based BHJ. In stage one, high-quality GaN-NWs were synthesized by the catalyst-free CVD method. The mechanism for controlling GaN-NWs morphology by adjusting the NH3 flow rate was revealed. In stage two, the GaN-NWs with large electron mobility were used to accelerate the transfer of photogenerated carriers in the BHJ layer. Finally, compared with the BHJ device, the BHJ/GaN device demonstrated obvious improvements in responsivity and photocurrent at the wavelength between 400 and 1000 nm. The responsivity and photocurrent increased over 20-fold at the NIR band of 800–900 nm. Besides, owing to the energy level gradient effect, the BHJ/GaN device has a response speed of 7.8/ < 5.0 ms, which increases over three orders of magnitude than that of the GaN-NWs-based device (tr/tf: 7.1/10.9 s). Therefore, the novel device structure proposed in this work holds great potential for preparing high-performance Vis-NIR photodetectors.

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