bottleneck and improve the system efficiency since the direct integration of ultrahigh memory layer on the processor chip is feasible. In another aspect, photonic memories are expected to speed up the von Neumann bottleneck and supercharge the performance of serial computers since the light signal can be regarded as the additional terminal of the underlying basic devices to ensure low power consumption. [7][8][9] The growing pursuit of practical photonic memories drives the rapid development of photonic technologies, especially in the region of nanofabricationcompatible optical signaling. In photonic memory, optical signals have to be converted into electrical signals and vice versa. However, it is difficult to make use of nearinfrared (NIR) light in photonic memory due to the inferior NIR sensitivity of most semiconductor materials originating from their broadband absorption. [10,11] In addition, although the decryption technology for visible light is mature in photonic memories, NIR photonic memristors are less progressed. [12][13][14] Upconversion materials are an anti-Stokes-shift type of photoluminescent compound that absorb several photons with long wavelength and emit one photon with shorter wavelength. [15,16] The upconversion nanoparticles (UCNPs) have been proposed as vital materials in various kinds of photonic applications including in vivo therapeutics, [17] biomedical imaging probes, [18] and optoelectronic [7,19] and optogenetic devices [20] due to their sharp emission bandwidth, high photochemical stability, and large anti-Stokes shift (up to several hundred nanometers). The UCNPs based on lanthanide ion (Yb 3+ , Er 3+ )-doped NaYF 4 have a narrow absorption band at 980 nm due to electronic transition between the energy levels in the lanthanide ion. [15] Thus, UCNPs exhibit extension of the applications in high-performance optoelectronics and multi-modal imaging in NIR band. However, the weak photo-absorption and insulating property of UCNPs limits their photon-electron conversion efficiency. The family of 2D materials including insulating hexagonal boron nitride (h-BN), semiconducting molybdenum disulfide (MoS 2 ) to semimetallic graphene and infrared-gapped black phosphorus has been demonstrated with distinct optical, electronic, and mechanical properties from conventional bulk materials. [21][22][23][24][25] Integration of UCNPs with 2D semiconducting materials results in heterostructures featuring increased sensitizing centers and energy transfer, which ensures the formation of more excitons and subsequently high sensitivity Photonic memories as an emerging optoelectronic technology have attracted tremendous attention in the past few years due to their great potential to overcome the von Neumann bottleneck and to improve the performance of serial computers. Nowadays, the decryption technology for visible light is mature in photonic memories. Nevertheless, near-infrared (NIR) photonic memristors are less progressed. Herein, an NIR photonic memristor based on MoS 2 -NaYF 4 :Yb 3+ , Er 3+ upconve...

No abstract

Thermal quenching of photoluminescence represents a significant obstacle to practical applications such as lighting, display, and photovoltaics. Herein, a novel strategy is established to enhance upconversion luminescence at elevated temperatures based on the use of negative thermal expansion host materials. Lanthanide‐doped orthorhombic Yb2W3O12 crystals are synthesized and characterized by in situ X‐ray diffraction and photoluminescence spectroscopy. The thermally induced contraction and distortion of the host lattice is demonstrated to enhance the collection of excitation energy by activator ions. When the temperature is increased from 303 to 573 K, a 29‐fold enhancement of green upconversion luminescence in Er3+ activators is achieved. Moreover, the temperature dependence of the upconversion luminescence is reversible. The thermally enhanced upconversion is developed as a sensitive ratiometric thermometer by referring to a thermally quenched upconversion.

Site-selective deposition of metal−organic frameworks (MOFs) on metal nanocrystals has remained challenging because of the difficult control of the nucleation and growth of MOFs. Herein we report on a facile wet-chemistry approach for the selective deposition of zeolitic imidazolate framework-8 (ZIF-8) on anisotropic Au nanobipyramids (NBPs) and nanorods. ZIF-8 is selectively deposited at the ends and waist and around the entire surface of the elongated Au nanocrystals. The NBPbased nanostructures with end-deposited ZIF-8 exhibit the best surfaceenhanced Raman scattering (SERS) performance, implying that molecules can be concentrated by ZIF-8 at the hot spots. In addition, the SERS signal exhibits good selectivity for small molecules because of the molecular sieving effect of ZIF-8. This study opens up a promising route for constructing plasmonic nanostructures with site selectively deposited ZIF-8, which hold enormous potential for molecular sensing, optical switching, and plasmonic catalysis.