Single-crystal organometallic perovskite optical fibers

One-Dimensional Single-Crystal Mesoporous TiO2 Supported CuW6O24 Clusters as Photocatalytic Cascade Nanoreactor for Boosting Reduction of CO2 to CH4

Constructing nanoreactors with multiple active sites in well-defined crystalline mesoporous frameworks is an effective strategy for tailoring photocatalysts to address the challenging of CO2 reduction. Herein, one-dimensional (1-D) mesoporous single-crystal TiO2 nanorod (MS-TiO2-NRs, ≈110 nm in length, high surface area of 117 m2 g-1, and uniform mesopores of ≈7.0 nm) based nanoreactors are prepared via a droplet interface directed-assembly strategy under mild condition. By regulating the interfacial energy, the 1-D mesoporous single-crystal TiO2 can be further tuned to polycrystalline fan- and flower-like morphologies with different oxygen vacancies (Ov). The integration of single-crystal nature and mesopores with exposed oxygen vacancies make the rod-like TiO2 nanoreactors exhibit a high-photocatalytic CO2 reduction selectivity to CO (95.1%). Furthermore, photocatalytic cascade nanoreactors by in situ incorporation of CuW6O24 (W-Cu) clusters onto MS-TiO2-NRs via Ov are designed and synthesized, which improved the CO2 adsorption capacity and achieved two-step CO2-CO-CH4 photoreduction. The second step CO-to-CH4 reaction induced by W-Cu sites ensures a high generation rate of CH4 (420.4 µmol g-1 h-1), along with an enhanced CH4 selectivity (≈94.3% electron selectivity). This research provides a platform for the design of mesoporous single-crystal materials, which potentially extends to a range of functional ceramics and semiconductors for various applications.

High-Throughput Growth of Armored Perovskite Single Crystal Fibers for Pixelated Arrays

The poor machinability of halide perovskite crystals severely hampered their practical applications. Here a high-throughput growth method is reported for armored perovskite single-crystal fibers (SCFs). The mold-embedded melt growth (MEG) method provides each SCF with a capillary quartz shell, thus guaranteeing their integrality when cutting and polishing. Hundreds of perovskite SCFs, exemplified by CsPbBr3, CsPbCl3, and CsPbBr2.5I0.5, with customized dimensions (inner diameters of 150-1000 µm and length of several centimeters), are grown in one batch, with all the SCFs bearing homogeneity in shape, orientation, and optical/electronic properties. Versatile assembly protocols are proposed to directly integrate the SCFs into arrays. The assembled array detectors demonstrated low-level dark currents (< 1 nA) with negligible drift, low detection limit (< 44.84 nGy s-1), and high sensitivity (61147 µC Gy-1 cm-2). Moreover, the SCFs as isolated pixels are free of signal crosstalk while showing uniform X-ray photocurrents, which is in favor of high spatial resolution X-ray imaging. As both MEG and the assembly of SCFs involve none sophisticated processes limiting the scalable fabrication, the strategy is considered to meet the preconditions of high-throughput productions.

Crystal Growth of Defect-Free Single-Crystalline Fibers in Super-High Supersaturation Solution

By controlling the supersaturation and choosing high-quality seeds, we successfully suppress the prismatic growth of the tetragonal potassium dihydrogen phosphate (KDP) SCFs, realize the rapid growth along the [001] direction, and obtain SCFs less than 10 μm in width with lengths of centimeters. The experimental results show that there exist critical supersaturation points, 22.40% and 41.41% at 25 °C, for initiating the growth of KDP SCF on its pyramidal and prismatic faces, respectively, which are quite different from those of the bulk crystals. We use the mechanism of 2D nucleation on smooth faces to explain the peculiar phenomena, assuming that there is no 2D or 3D defect on the surfaces of the seed fiber crystal. The assumption is supported by AFM observation of the surface micromorphology of the SCFs. Our solution growth technique developed can be used to grow ultrafine SCFs unable to be achieved by existing melt growth techniques.

Recent Advancements in Tin Halide Perovskite-Based Solar Cells and Thermoelectric Devices

The excellent optoelectronic properties of tin halide perovskites (Sn-PVKs) have made them a promising candidate for replacing toxic Pb counterparts. Concurrently, their enormous potential in photon harvesting and thermoelectricity applications has attracted increasing attention. The optoelectronic properties of Sn-PVKs are governed by the flexible nature of SnI₆ octahedra, and they exhibit extremely low thermal conductivity. Due to these diverse applications, this review first analyzes the structural properties, optoelectronic properties, defect physics, and thermoelectric properties of Sn-PVKs. Then, recent techniques developed to solve limitations with Sn-PVK-based devices to improve their photoelectric and thermoelectric performance are discussed in detail. Finally, the challenges and prospects for further development of Sn-PVK-based devices are discussed.