2D Metal‐Organic Complex Luminescent Crystals

Abstract

2D emissive crystals have attracted tremendous research interests due to their outstanding compatibility with an integrated planar photonic system, which ideally meet the requirement for versatile photonic device applications, such as lasers, light-emitting devices, and optical waveguides. Among 2D emissive materials, metal-organic complex crystals are highly desirable because of their strong charge-transfer interactions and enhanced optical absorption that benefit superior luminescence efficiency. Here, the in-air sublimation method is adopted to synthesize 2D Ge-TCNQ microplate crystals (TCNQ, 7,7,8,8-tetracyanoquinodimethane) with thickness down to 13.4 nm. Such ultrathin Ge-TCNQ crystals exhibit an exciton binding energy of 40.7 meV and a decent photoluminescence (PL) quantum efficiency of 5.53%. The fitting slope of excitation power-dependent PL intensity displays a transition from linear to superlinear characteristics that reveals both trap-assisted recombination and free carrier recombination are present in the luminescence process. The energy band structure of Ge-TCNQ is examined by ultraviolet photoelectron spectroscopy and UV-vis spectroscopy to elucidate the physical mechanism of photo excitation and fluorescence processes. The emissive Ge-TCNQ crystals are further employed as high-performance optical waveguides with a small optical loss coefficient of 0.078 dB µm −1 . This work opens new avenues using 2D metal-organic complex crystals to develop advanced optoelectronic devices.

Controllable Synthesis of Metal–Organic Frameworks Based on Anthracene Ligands for High-Sensitivity Fluorescence Sensing of Fe3+, Cr2O72–, and TNP

“…Further, compared with the emission peak of tatrz, the emission peaks of CUST-601–605 are blue-shifted. This phenomenon can be attributed to the electron transfer from the ligand to metal ion in the coordination process. , Otherwise, for CUST-605 , the strong conjugation effect of BTB ligand may cause a part of energy transfer from tatrz to BTB; thus, CUST-605 shows small Stokes shifts . Notably, the excitation wavelengths of all crystals were obtained from the UV–vis spectrum (Figure S15).…”

“…In Figure 3b,c, two Cd II centers are linked by one oxygen atom to form a dinuclear Cd 2 , further connecting BTC and tatrz ligands, resulting in the 3D network structure of CUST-603, with one-dimensional channels along the a-axis. Using the dinuclear Cd 2 as 6-connected, CUST-603 can be simplified to a 6-connect double interpenetration network, with the topology symbol of {4 12 •6 3 } (Figure 3d).…”

“…Metal–organic frameworks (MOFs) are a kind of porous crystalline materials, constructed by organic ligands and metal ions, which have been extensively researched in catalysis, gas storage, adsorption and degradation, fluorescence sensors, − and other fields due to the porosity and adjustable structures. − Particularly, MOFs have been diffusely recognized as fluorescence sensors for detecting metal ions and nitroaromatic explosives (NACs) on account of the energy and electron transfer contact with analytes. , For example, Qi and co-workers synthesized a Tb-MOF, which exhibits high sensitivity and selectivity for the detection of Fe 3+ , with the limit of detection (LOD) of 0.936 μM . Qin and co-workers designed and prepared two porous Zn-based MOF materials, which can detect Fe 3+ , CrO 4 2– , and Cr 2 O 7 2– ions quickly in a short time with the low LOD of 1.06, 3.87, and 2.37 μM, respectively .…”

Reversible Triple-Mode Switching in Photoluminescence from 0D Hybrid Antimony Halides

“…5,6 Over the past several years, a wide variety of smart luminescent materials have been extensively explored, including organic dyes, metal−organic complexes, liquid crystals, polymeric hydrogels, etc. 7,8 However, the previously reported fluorescence materials are subjected to some unavoidable technical bottlenecks of low emission intensities, complicated assembly processes, low color contrasts, and emission intensity changes, which significantly limit their further applications in high-performance dynamic photoelectric devices. 9 Especially, rare solid-state turn-on or reversible photoluminescent (PL) on−off switching is achieved under easily controllable external stimuli, but it is more applicable for high-resolution optical gates.…”

Fluorescence-based monitoring of the pressure-induced aggregation microenvironment evolution for an AIEgen under multiple excitation channels

“…Solid-state luminescent materials have gained extensive attention because of their promising applications in anti-counterfeiting technology 1 , 2 , fluorescent probes 3 – 5 , sensors 6 , 7 , optical devices 8 , 9 , and biological science 10 – 14 . In some organic luminescent materials, planarization of the molecular conformation or aggregation results in π -conjugated intermolecular interactions, resulting in the formation of species that adversely affect the luminescence properties.…”