Systematic Approach in Designing Rare-Earth-Free Hybrid Semiconductor Phosphors for General Lighting Applications

As one of the most rapidly evolving branches of solid-state lighting technologies, light emitting diodes (LEDs) are gradually replacing conventional lighting sources due to their advantages in energy saving and environmental protection. At the present time, commercially available white light emitting diodes (WLEDs) are predominantly phosphor based (e.g., a yellow-emitting phosphor, such as cerium-doped yttrium aluminum garnet or (YAG):Ce³⁺, coupled with a blue-emitting InGaN/GaN diode), which rely heavily on rare-earth (RE) metals. To avoid potential supply risks of these elements, we have developed an inorganic–organic hybrid phosphor family based on I–VII binary semiconductors. The hybrid phosphor materials are totally free of rare-earth metals. They can be synthesized by a simple, low-cost solution process and are easily scalable. Their band gap and emission energy, intensity, and color can be systematically tuned by incorporating ligands with suitable electronic properties. High quantum efficiency is achieved for some of these compounds. Such features make this group of materials promising candidates as alternative phosphors for use in general lighting devices

Chromophore-Based Luminescent Metal–Organic Frameworks as Lighting Phosphors

Energy-efficient solid-state-lighting (SSL) technologies are rapidly developing, but the lack of stable, high-performance rare-earth free phosphors may impede the growth of the SSL market. One possible alternative is organic phosphor materials, but these can suffer from lower quantum yields and thermal instability compared to rare-earth phosphors. However, if luminescent organic chromophores can be built into a rigid metal–organic framework, their quantum yields and thermal stability can be greatly improved. This Forum Article discusses the design of a group of such chromophore-based luminescent metal–organic frameworks with exceptionally high performance and rational control of the important parameters that influence their emission properties, including electronic structures of chromophore, coligands, metal ions, and guest molecules

Selective, Sensitive, and Reversible Detection of Vapor-Phase High Explosives via Two-Dimensional Mapping: A New Strategy for MOF-Based Sensors

A new strategy has been developed for the effective detection of high explosives in vapor phase by fluorescent metal–organic framework (MOF) sensors. Two structurally related and dynamic MOFs, (Zn)₂(ndc)₂P·<i>x</i>G [ndc = 2,6-naphthalenedicarboxylate; P =1,2-bis­(4-pyridyl)­ethane (bpe) or 1,2-bis­(4-pyridyl)­ethylene (bpee); G = guest/solvent molecule], exhibit a two-dimensional signal response toward analytes of interest in the vapor phase, including aromatic and aliphatic high explosives (e.g., TNT and RDX). The interaction between analytes and the MOF has been studied using in situ infrared absorption spectroscopy and a DFT computational method

Highly Luminescent Metal–Organic Frameworks Based on an Aggregation-Induced Emission Ligand as Chemical Sensors for Nitroaromatic Compounds

Three new luminescent metal–organic frameworks (LMOFs) based on d¹⁰ metals (Zn²⁺, Cd²⁺) and the highly emissive aggregation-induced emission ligand 1,1,2,2-tetrakis­(4-(4-carboxyphenyl)­phenyl)­ethene­(H₄tcbpe) are reported, with the formulas [Cd₃(tcbpe)_1.5­(DMF)­(H₂O)₂]­·(DMF)₆­·(C₂H₅OH)₃ (<b>1</b>), [Zn­(tcbpe)­(DMF)]­·(MeCN) (<b>2</b>), and [Cd­(tcbpe)]­·(MeCN) (<b>3</b>). Compounds <b>1</b> and <b>2</b> both emit strong green light with internal quantum yields (IQYs) as high as 66.8% and 65.7%, respectively, while compound <b>3</b> emits bluish green light with 37.2% IQY. A solution-phase sensing study shows that <b>1</b> has the highest sensitivity to nitroaromatic compounds and demonstrates that it is potentially useful as a luminescence-based chemical sensor. Density functional theory calculations are used to explain the sensing mechanism and relative sensitivity of compound <b>1</b> to various nitroaromatic compounds

A Family of Highly Efficient CuI-Based Lighting Phosphors Prepared by a Systematic, Bottom-up Synthetic Approach

Copper­(I) iodide (CuI)-based inorganic–organic hybrid materials in the general chemical formula of CuI­(L) are well-known for their structural diversity and strong photoluminescence and are therefore considered promising candidates for a number of optical applications. In this work, we demonstrate a systematic, bottom-up precursor approach to developing a series of CuI­(L) network structures built on CuI rhomboid dimers. These compounds combine strong luminescence due to the CuI inorganic modules and significantly enhanced thermal stability as a result of connecting individual building units into robust, extended networks. Examination of their optical properties reveals that these materials not only exhibit exceptionally high photoluminescence performance (with internal quantum yield up to 95%) but also that their emission energy and color are systematically tunable through modification of the organic component. Results from density functional theory calculations provide convincing correlations between these materials’ crystal structures and chemical compositions and their optophysical properties. The advantages of cost-effective, solution-processable, easily scalable and fully controllable synthesis as well as high quantum efficiency with improved thermal stability, make this phosphor family a promising candidate for alternative, RE-free phosphors in general lighting and illumination. This solution-based precursor approach creates a new blueprint for the rational design and controlled synthesis of inorganic–organic hybrid materials

A Family of Highly Efficient CuI-Based Lighting Phosphors Prepared by a Systematic, Bottom-up Synthetic Approach

Copper­(I) iodide (CuI)-based inorganic–organic hybrid materials in the general chemical formula of CuI­(L) are well-known for their structural diversity and strong photoluminescence and are therefore considered promising candidates for a number of optical applications. In this work, we demonstrate a systematic, bottom-up precursor approach to developing a series of CuI­(L) network structures built on CuI rhomboid dimers. These compounds combine strong luminescence due to the CuI inorganic modules and significantly enhanced thermal stability as a result of connecting individual building units into robust, extended networks. Examination of their optical properties reveals that these materials not only exhibit exceptionally high photoluminescence performance (with internal quantum yield up to 95%) but also that their emission energy and color are systematically tunable through modification of the organic component. Results from density functional theory calculations provide convincing correlations between these materials’ crystal structures and chemical compositions and their optophysical properties. The advantages of cost-effective, solution-processable, easily scalable and fully controllable synthesis as well as high quantum efficiency with improved thermal stability, make this phosphor family a promising candidate for alternative, RE-free phosphors in general lighting and illumination. This solution-based precursor approach creates a new blueprint for the rational design and controlled synthesis of inorganic–organic hybrid materials

A Family of Highly Efficient CuI-Based Lighting Phosphors Prepared by a Systematic, Bottom-up Synthetic Approach

Copper­(I) iodide (CuI)-based inorganic–organic hybrid materials in the general chemical formula of CuI­(L) are well-known for their structural diversity and strong photoluminescence and are therefore considered promising candidates for a number of optical applications. In this work, we demonstrate a systematic, bottom-up precursor approach to developing a series of CuI­(L) network structures built on CuI rhomboid dimers. These compounds combine strong luminescence due to the CuI inorganic modules and significantly enhanced thermal stability as a result of connecting individual building units into robust, extended networks. Examination of their optical properties reveals that these materials not only exhibit exceptionally high photoluminescence performance (with internal quantum yield up to 95%) but also that their emission energy and color are systematically tunable through modification of the organic component. Results from density functional theory calculations provide convincing correlations between these materials’ crystal structures and chemical compositions and their optophysical properties. The advantages of cost-effective, solution-processable, easily scalable and fully controllable synthesis as well as high quantum efficiency with improved thermal stability, make this phosphor family a promising candidate for alternative, RE-free phosphors in general lighting and illumination. This solution-based precursor approach creates a new blueprint for the rational design and controlled synthesis of inorganic–organic hybrid materials

A Family of Highly Efficient CuI-Based Lighting Phosphors Prepared by a Systematic, Bottom-up Synthetic Approach

Copper­(I) iodide (CuI)-based inorganic–organic hybrid materials in the general chemical formula of CuI­(L) are well-known for their structural diversity and strong photoluminescence and are therefore considered promising candidates for a number of optical applications. In this work, we demonstrate a systematic, bottom-up precursor approach to developing a series of CuI­(L) network structures built on CuI rhomboid dimers. These compounds combine strong luminescence due to the CuI inorganic modules and significantly enhanced thermal stability as a result of connecting individual building units into robust, extended networks. Examination of their optical properties reveals that these materials not only exhibit exceptionally high photoluminescence performance (with internal quantum yield up to 95%) but also that their emission energy and color are systematically tunable through modification of the organic component. Results from density functional theory calculations provide convincing correlations between these materials’ crystal structures and chemical compositions and their optophysical properties. The advantages of cost-effective, solution-processable, easily scalable and fully controllable synthesis as well as high quantum efficiency with improved thermal stability, make this phosphor family a promising candidate for alternative, RE-free phosphors in general lighting and illumination. This solution-based precursor approach creates a new blueprint for the rational design and controlled synthesis of inorganic–organic hybrid materials

Effective Detection of Mycotoxins by a Highly Luminescent Metal–Organic Framework

We designed and synthesized a new luminescent metal–organic framework (LMOF). LMOF-241 is highly porous and emits strong blue light with high efficiency. We demonstrate for the first time that very fast and extremely sensitive optical detection can be achieved, making use of the fluorescence quenching of an LMOF material. The compound is responsive to Aflatoxin B₁ at parts per billion level, which makes it the best performing luminescence-based chemical sensor to date. We studied the electronic properties of LMOF-241 and selected mycotoxins, as well as the extent of mycotoxin–LMOF interactions, employing theoretical methods. Possible electron and energy transfer mechanisms are discussed

Solution Processable MOF Yellow Phosphor with Exceptionally High Quantum Efficiency

An important aspect in the research and development of white light-emitting diodes (WLEDs) is the discovery of highly efficient phosphors free of rare-earth (RE) elements. Herein we report the design and synthesis of a new type of RE-free, blue-excitable yellow phosphor, obtained by combining a strongly emissive molecular fluorophore with a bandgap modulating co-ligand, in a three-dimensional metal organic framework. [Zn₆(btc)₄(tppe)₂(DMA)₂] (btc = benzene-1,3,5-tricarboxylate, tppe = 1,1,2,2-tetrakis­(4-(pyridin-4-yl)­phenyl)­ethene, DMA = dimethylacetamide) crystallizes in a new structure type and emits bright yellow light when excited by a blue light source. It possesses the highest internal quantum yield among all RE-free, blue-excitable yellow phosphors reported to date, with a value as high as 90.7% (λ_ex = 400 nm). In addition to its high internal quantum yield, the new yellow phosphor also demonstrates high external quantum yield, luminescent and moisture stability, solution processability, and color tunability, making it a promising material for use in phosphor conversion WLEDs