Tunable Emission Research Articles

Ion-doped lead-free double perovskite Cs2NaBiCl6 with multiple excitation and tunable emission towards light emitting and anti-counterfeiting applications

Ion doped lead-free double perovskite Cs2NaBiCl6 with multiple excitation and tunable emission was fabricated towards light emitting (CNBC:30%Br−, 15%Mn2+) and anti-counterfeiting applications (CNBC:30%Br−, 15%Mn2+, 12%Er3+, 12%Yb3+), respectively.

Tunable ultra-broadband multi-band NIR emission in Bi-doped aluminogermanate glasses and fibers via controllable Al2O3 content for broadband amplifiers

The tunable ultra-broadband multi-band NIR emission of Bi-doped germanate glass and fiber can be achieved via constructing various glass local network environments with steerable Al2O3 content and show potential applications in broadband amplifiers.

Metal co-doped cesium manganese chlorine nanocrystals with high efficiency and tunable red emission

Metal co-doped cesium manganese halide nanocrystals are synthesized to enhance the red emission depending on the transitional role of Tm3+ ions, and realize tunable red emission from 660 nm to 628 nm by controlling the Pb doping contents.

Recent advances in tunable solid-state emission based on α-cyanodiarylethenes: from molecular packing regulation to functional development.

The design and development of organic solid-state luminescent materials stand as crucial pillars within the realm of contemporary photofunctional materials. Overcoming challenges such as concentration quenching and achieving tailored luminescent properties necessitates a judicious approach to molecular structure design and the strategic utilization of diverse stimuli to modulate molecular packing patterns. Among the myriad candidates, α-cyanodiarylethenes (CAEs) emerge with distinctive solid-state luminescent attributes, capable of forming self-assembled packing structures with varying degrees of π-π stacking. This characteristic endows them with potential in the field of intelligent molecular responsive materials and optoelectronic devices. This tutorial review embarks on an exploration of design strategies geared towards attaining tunable solid-state emission through customized packing of CAEs. It explores the utilization of stimuli responses, including such as mechanical forces, light irradiation, solvent interactions, thermal influences, as well as the utilization of co-assembly methodologies. The overarching aim of this review is to provide a widely applicable platform fostering the flourishing development of modern organic photofunctional materials through integrating principles of molecular engineering, organic optoelectronics, and materials science.

Alkali metal salt-assisted crystal structure switch of hybrid indium halides with near-unity photoluminescence quantum yield

We synthesized 0D MA4InCl7 and MA2KInCl6 metal halides, and Sb3+ doping enabled near-unity photoluminescence quantum yield. A one-way switch from MA4InCl7 to MA2KInCl6 can be achieved by adding additional potassium precursors.

Photoluminescence quantum yield of carbon dots: emission due to multiple centers versus excitonic emission.

Carbon dots (CDs) are recognized as promising fluorescent nanomaterials with bright emission and large variations of photoluminescence quantum yield (PLQY). However, there is still no unique approach for explanation of mechanisms and recipes for synthetic procedures/chemical composition of CDs responsible for the enhancement of PLQY. Here, we compare photophysical behavior and PLQY of two types of CDs synthesized by different routes, leading to the different extent of oxidation and composition. The first type of CDs represents a conjugated carbon system oxidized by F, N and O heteroatoms, whereas the second type represents a non-conjugated carbon system oxidized by oxygen. Photophysical data, photoemission spectroscopy and microscopy data yield the suggestion that in the first case, a structure with a distinct carbon core and highly oxidized electron-accepting shell is formed. This leads to the excitonic type non-tunable emission with single-exponent decay and high PLQY with a strong dependence on the solvent polarity, being as high as 93% in dioxane and as low as 30% in aqueous medium, but which is vulnerable to photobleaching. In the second case, the oxidized CDs do not indicate a clear core-shell structure and show poor solvatochromism, negligible photobleaching, low PLQY varying in the range of 0.7-2.3% depending on the solvent used, and tunable emission with multi-exponent decay, which can be described by the model of multiple emission centers acting through a clustering-triggered emission mechanism. The obtained results lead to a strategy that allows one to design carbon nanomaterials with principally different PLQYs that differ by orders of magnitude.

Structure, luminescence properties, and valence-induced spectral behavior of a bismuth-activated garnet phosphor

The increasing demand for full-visible-spectrum lighting has prompted the development of novel phosphors with multicolor emission.

Pressure-Induced Tunable Emission Colors and Irreversible Bandgap Narrowing in Organic–Inorganic Manganese Bromide Hybrid

Manganese (Mn)-based organic-inorganic metal halides (OIMHs) are extensively employed in various optical applications due to their non-toxicity, superior optical properties, and tunable emission advantages. Developing effective strategies to enhance the...

Tunable emission and thermal sensitivity via energy transfer from Bi3+ to Eu3+ in BaY2Al2Ga2GeO12

Eu3+ occupies the central lattice of the octahedron with inverted symmetry in BYAGGO:Eu3+, while Eu3+ expands to the asymmetric dodecahedron center in BYAGGO:Eu3+, Bi3+. There is also efficient transfer from Bi3+ to Eu3+ in BYAGGO:Eu3+, Bi3+.

Tunable emission from H-type supramolecular polymers in optical nanocavities.

H-type supramolecular polymers with preferred helicity and highly efficient emission have been prepared from the self-assembly of chiral tetraphenylene-based monomers. Implementation of the one-dimensional fibers into dielectric nanoparticle arrays allows for a significant reshaping of fluorescence due to weak light-matter coupling.

A ratiometric luminescence thermometer based on lanthanide encapsulated complexes.

Lanthanide-containing complexes have been widely developed as ratiometric luminescence thermometers, which are non-invasive, contactless and accurate. The synthesis of these Ln complexes generally requires high temperatures, multiple steps and other harsh conditions. Moreover, bimetallic lanthanide complexes, which have been reported to be better thermometers, are even more challenging to synthesize. This complexity can be simplified by preparing a host-guest complex of lanthanides. In this work, Tb or both Tb and Eu are encapsulated in an MOF host, making them emissive. The ratio of Tb/Eu was also easily tuned by simply changing their ratio in the solution, resulting in a tunable emission. Accordingly, we were able to synthesise both the emissive Tb complex and Tb/Eu complexes at different ratios using a single host. The complexes were found to be suitable as ratiometric luminescent thermometers in the temperature range of 160-380 K, with reasonably good sensitivity and uncertainty. The thermometer's sensitivity and uncertainty were significantly improved using bimetallic Tb and Eu host-guest complexes. Calculations using the host and Eu emission ratio were found to provide better thermometer parameters than the commonly reported Tb and Eu emission ratio. Thus, using a single host, we were able to synthesise different lanthanide complexes that can sense temperature, and we improved the thermometer parameters by incorporating multiple lanthanides in a single host. This research will enable the scientific community to reexamine the applicability of unexplored host-guest lanthanide complexes.

Room temperature synthesis of highly luminescent Eu3+ and Tb3+-doped hexagonal-phase YPO4 nanoparticles with tunable emission

Luminescent lanthanide nanoparticles are usually prepared at high temperatures, which makes these materials costly. Room temperature synthesis will make the material cheap.

Rationally designed synthesis of bright Cu–Ga–Zn–Se-based nanocrystals for efficient green quantum-dot light-emitting diodes

Cd-free QLEDs with tunable emission from 603 to 524 nm were constructed by regulating the non-stoichiometric Cu : Ga molar ratio, and the green QLEDs showed high performance with an EQE of 5.8% and a high brightness of 7016 cd m−2.

Reversible tri-state structural transitions of hybrid copper(i) bromides toward tunable multiple emissions

Synthetic control and tri-state structural transitions (112 ↔ 224 ↔ 246) of three hybrid copper bromides with different coordination geometries, which exhibit tunable optical property, are fristly discovered and investigated in hybrid copper halides.

Dual precipitating reagents-assisted deep blue-emitting borate and near-white oxide-based luminescent materials.

We explored dual precipitating reagents-assisted Ce-based deep blue-emitting borate and near-white oxide-based luminescent materials. The first precipitating reagent (aqueous sodium borohydride) was used until gelation. The second precipitating reagent (ammonia solution) was employed to prepare as-synthesized powders. XRD analysis, FTIR spectroscopy, and Raman spectroscopy of calcined powders ranging from 1000 °C to 1400 °C confirmed the development of a primary borate phase (i.e., nearly polyhedral-shaped YBO3) with secondary phases of (Y,Al)BO3 and oxide. However, the preliminary oxide phase (i.e., elongated/rod-like YAG) and secondary phases of YBO3, Al2O3, and CeO2 were developed at 1500 °C with different holding times. The emission behavior and CIE coordinates confirmed that the borate (i.e., YBO3-based) sample was deep blue. However, the oxide (i.e., YAG-based) sample showed tunable color emissions from light blue to near white with increased holding time. The average lifetime of prepared samples varied between 788 ns and 891 ns, which indicated a long decay time. The quantum yield of the sample calcined at 1400-1500 °C varied between ∼61% and ∼77%. Based on the emission behavior, CIE diagram, CCT, powder color, average lifetime, and quantum yield, the developed deep blue-emitting borate and light blue/near white oxide-based luminescent materials could be used in lighting industries.

A universal supramolecular assembly strategy for achieving efficient tunable white emission and anti-counterfeiting in antimony doped tin(iv)-based vacancy-ordered double perovskites

Three compounds with high PLQY, (AC)2SnCl6:Sb3+ (A = K, Rb, and Cs), were developed using a supramolecular assembly strategy. The samples doped with Sb3+ were used to achieve tunable WLEDs, anti-counterfeiting, and information encryption.

Self-assembled D–π–A multifunctional systems with tunable stimuli-responsive emission and optical waveguiding behaviour

Crystalline assembly of naphthalenimide derivatives with a D–π–A structure gives rise to light guiding and mechanical and thermal stimuli-responsiveness.

Energy transfer for Ce3+ → Tb3+ → Sm3+ induced bright white emission in single-phase CaLa4(SiO4)3O:Ce3+, Tb3+, Sm3+ phosphors and their application in white-light-emitting diodes.

The emergence of phosphor-converted white-light-emitting diodes has crucial significance in the sustainable development of energy; hence, the evolution of phosphors with eminent luminescence and high stability is imperative. In this study, a tri-doped system composed of rare earth ions Ce3+, Tb3+, and Sm3+ incorporated into a CaLa4(SiO4)3O host is reported, and the energy transfer, tunable single-phase white emission, and favorable thermostability of the Ce3+-Tb3+-Sm3+ system were explored. Rietveld refinement results coincided with the original model of the crystal structure, and a band gap energy of 4.612 eV calculated using density functional theory (DFT) demonstrated the system as an appropriate luminescent host with a wide energy gap. Furthermore, ET processes for Ce3+ → Tb3+, Tb3+ → Sm3+, and Ce3+ → Tb3+ → Sm3+ were investigated via steady-state photoluminescence and decay measurements. Besides, the activation energies of CLSO:3%Ce3+, 9%Tb3+, y%Sm3+ (y = 7, 9) were 0.205 eV and 0.223 eV, respectively, showing outstanding thermal quenching resistance. Devices made with LED beads containing CLSO:3%Ce3+, 9%Tb3+, y%Sm3+ (y = 7, 9) phosphors exhibited bright white light with CCT ≈ 3586 and 3307 K and Ra ≈ 81.0 and 78.5, respectively. This study demonstrates that energy transfer for Ce3+-Tb3+-Sm3+ in a tri-doped system offers an interesting design prospect for promoting single-phase white emission phosphors.

Composition tunable and stable spontaneous emission and lasing in Cd-alloyed perovskite microdisks.

All-inorganic Pb-Cd mixed-cation halide perovskites have emerged as semiconductors exhibiting improved optical and optoelectronic properties. We establish a reliable correlation between photoluminescence and Cd content x in bulk CsPb1-xCdxBr3 compositions, propose pathways of photoexcited charge carrier dynamics in them, and show improved stability of lasing in whispering gallery mode microdisks.

Phase change plasmonic metasurface for dynamic thermal emission modulation

Plasmonic metasurfaces with adjustable optical responses can be achieved through phase change materials (PCMs) with high optical contrast. However, the on–off behavior of the phase change process results in the binary response of photonic devices, limiting the applications to the two-stage modulation. In this work, we propose a reconfigurable metasurface emitter based on a gold nanorod array on a VO2 thin film for achieving continuously tunable narrowband thermal emission. The electrode line connecting the center of each nanorod not only enables emission excitation electrically but also activates the phase transition of VO2 beneath the array layer due to Joule heating. The change in the dielectric environment due to the VO2 phase transition results in the modulation of emissivity from the plasmonic metasurfaces. The device performances regarding critical geometrical parameters are analyzed based on a fully coupled electro-thermo-optical finite element model. This new metasurface structure extends the binary nature of PCM based modulations to continuous reconfigurability and provides new possibilities toward smart metasurface emitters, reflectors, and other nanophotonic devices.