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A new cesium hydroxyborate CsB3O4(OH)2, was designed and synthesized by a hydrothermal method. Remarkably, CsB3O4(OH)2 presents novel [B3O4(OH)2]∞ chains formed by [B3O4(OH)2] fundamental building blocks (FBBs). The report of less common [B3O4(OH)2] FBBs and [B3O4(OH)2]∞ chains in CsB3O4(OH)2 enriches the structural diversity of hydroxyborates. In addition, CsB3O4(OH)2 has a wide transparent window in the DUV spectral range and a large birefringence. [ABSTRACT FROM AUTHOR]

Tellurate crystals are attractive for developing new nonlinear optical (NLO) materials in the mid-infrared region due to their wide transmission window. In this work, we report a quaternary tellurate oxide crystal, Li2GeTeO6, which exhibits a short cutoff edge (240 nm) with a powder second harmonic generation (SHG) response of 1.3 × KH2PO4 (KDP). The reported material reveals the largest band gap in the Li2MTeO6 (M = tetravalent cation) family. The first-principles calculations were used to illustrate the origin of the NLO effect. These results highlight the band gap engineering based on the cation substitution strategy for designing new NLO materials with balanced optical properties. [ABSTRACT FROM AUTHOR]

Two lead borate-nitrates Pb6O4(BO3)(NO3) and Pb6O2(BO3)2(NO3)F were obtained by the high-temperature flux method. Interestingly, their crystal structure consists of anion-centered [OPb4] tetrahedra and π-conjugated BO3 and NO3 units. The first principles calculations indicate that both compounds show large birefringence. [ABSTRACT FROM AUTHOR]

A series of M6PS5X (M = Ag, Cu; X = Cl, Br) nonlinear optical (NLO) chalcohalides with special MS3X ligands have been synthesized in this work. Their critical optical performances were systematically measured and the research results show that all of them exhibit strong NLO responses (2.0–2.7 × commercial AgGaS2) and high laser-damage thresholds (1.7–2.3 × AgGaS2), indicating their potential application as good NLO candidates. Furthermore, first-principles calculations were used to study their inherent structure–property relationships and chalcohalides can be expected to be optimal systems for the exploration of new promising IR NLO crystals. [ABSTRACT FROM AUTHOR]

Sulfur nanodots (S-dots), composed of an elemental sulfur core and surface ligands, show unexpected photoluminescence (PL) properties, with the unique features of nontoxicity, hydrophilicity, high stability and easy modification. This review systematically introduces the synthesis methods, characterization, PL mechanisms and some typical applications of S-dots in chemical sensing. As the PL quantum yield (QY) is a key factor to evaluate the performance of luminescent materials, we report the synthesis methods according to the achievement in the promotion of PL QY. The PL mechanisms of S-dots are discussed from the view of the effects of the elemental sulfur core and passivated ligands on the PL QY and emission color. The design principle of analytical methods for various target molecules using S-dots is introduced. We end this review with the conclusions and some challenges in this field, which is expected to provide some clues for researchers in this field. [ABSTRACT FROM AUTHOR]

The spectral mismatch between the distribution of sunlight (AM1.5G) and crystalline silicon (c-Si) solar cells is one of the most important limiting factors of the conversion efficiency of photovoltaic (PV) devices. As an effective solution, the use of the luminescence down-shifting (LDS) technique is an important way to improve the short-wavelength response of a solar cell by shifting high-energy photons to the visible range. Herein, a large-area (17 × 17 cm2) luminescent thin film consisting of a ternary europium (Eu3+) complex and polyvinyl alcohol (PVA) was successfully constructed through a solution casting method and further developed as an effective LDS layer to improve the photoelectric conversion efficiency of c-Si solar cells with a large active area (235 cm2). The self-standing LDS layer is flexible, transparent and easily attachable to the surface of the solar cell module. Compared with the uncoated c-Si solar cell, the one coated with the LDS layer displayed an enhancement of ∼15% in external quantum efficiency (EQE) due to the high luminescence quantum yield of the Eu3+ complex doped inside the layer. These results demonstrate that use of a large area luminescent film embedding an Eu3+ complex is a versatile and effective strategy to improve the conversion efficiency of large size PV devices, giving rise to its great potential application as an LDS material. [ABSTRACT FROM AUTHOR]

Herein luminescent lanthanide supramolecular assemblies were constructed via coordination of a crown-connected bis-terpyridine (L1) and Ln3+ ions, which can self-assemble to form homogeneous spherical nanoparticles with an average diameter of 700 nm on a silicon plate surface upon slow evaporation of solvents. Potassium ions are shown to give rise to obvious enhancement in the luminescence of Ln3+ (Ln = Eu, Tb) ions in the lanthanide assemblies. The changes are the consequence of the capture of the cations by the crown moieties via cation–π interactions, increasing the triplet excited energy level of L1 and thus favoring the population of the lanthanide's excited state from the antenna triplet state by means of an energy transfer. Besides, energy transfer from Tb3+ to Eu3+ was observed in the luminescent Eu3+/Tb3+ bimetallic assemblies (Eu/Tb·L1) and the efficiency can be tuned by potassium concentration. Thus, Eu/Tb·L1 can serve as a self-calibrating sensor, which can selectively and quantitatively detect potassium by linearly correlating the K+ concentration to the emission intensity ratio of 5D4→7F5 transition (Tb3+) to 5D0→7F2 transition (Eu3+). [ABSTRACT FROM AUTHOR]

Luminescent hydrogels are of immense importance for various applications nowadays, but there is still a significant challenge to achieve excellent optical functional hydrogels combining robust mechanical properties and high self-healing efficiency under mild conditions. Herein, we describe the preparation of a series of color-tunable and robust luminescent hydrogels through the electrostatic interactions between positively-charged luminescent micelles and negatively-charged clay nanosheets. The further addition of poly (vinyl alcohol) (PVA) results in an obvious enhancement in the mechanical strength of the hydrogels via physical cross-linking, leading to a more stable luminescent hydrogel with fast self-healing performance. The obtained luminescent hydrogels can also retain their shape persistence even when immersed in organic solvents, affording novel luminescent organogels with outstanding optical performance. [ABSTRACT FROM AUTHOR]

A direct ion-exchange approach was adopted to intercalate ionic lanthanide complexes into layered α-zirconium phosphate. The obtained luminescent hybrid composites were characterized via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and photoluminescence spectroscopy. These composites exhibit an expanded layer distance as well as higher thermo- and photo-stability. Moreover, a simple, effective and robust luminescent sensor has been developed based on the aforementioned composites for detecting organic amines, with high selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

Tellurate crystals are attractive for developing new nonlinear optical (NLO) materials in the mid-infrared region due to their wide transmission window. In this work, we report a quaternary tellurate oxide crystal, Li2GeTeO6, which exhibits a short cutoff edge (240 nm) with a powder second harmonic generation (SHG) response of 1.3 × KH2PO4 (KDP). The reported material reveals the largest band gap in the Li2MTeO6 (M = tetravalent cation) family. The first-principles calculations were used to illustrate the origin of the NLO effect. These results highlight the band gap engineering based on the cation substitution strategy for designing new NLO materials with balanced optical properties. [ABSTRACT FROM AUTHOR]

A new cesium hydroxyborate CsB 3 O 4 (OH) 2 , was designed and synthesized by a hydrothermal method. Remarkably, CsB 3 O 4 (OH) 2 presents novel [B 3 O 4 (OH) 2 ] ∞ chains formed by [B 3 O 4 (OH) 2 ] fundamental building blocks (FBBs). The report of less common [B 3 O 4 (OH) 2 ] FBBs and [B 3 O 4 (OH) 2 ] ∞ chains in CsB 3 O 4 (OH) 2 enriches the structural diversity of hydroxyborates. In addition, CsB 3 O 4 (OH) 2 has a wide transparent window in the DUV spectral range and a large birefringence.

Tellurate crystals are attractive for developing new nonlinear optical (NLO) materials in the mid-infrared region due to their wide transmission window. In this work, we report a quaternary tellurate oxide crystal, Li 2 GeTeO 6 , which exhibits a short cutoff edge (240 nm) with a powder second harmonic generation (SHG) response of 1.3 × KH 2 PO 4 (KDP). The reported material reveals the largest band gap in the Li 2 MTeO 6 (M = tetravalent cation) family. The first-principles calculations were used to illustrate the origin of the NLO effect. These results highlight the band gap engineering based on the cation substitution strategy for designing new NLO materials with balanced optical properties.

Oxysulfides combining intrinsic performance advantages between sulfides (strong NLO response) and oxides (wide optical bandgap) are proposed as potential infrared (IR) NLO materials. Theoretical calculation shows that the mixed-anion GeS 3 O tetrahedron has a stronger polarizability anisotropy and hyperpolarizability than that of the typical GeO 4 unit. Based on this, two Sr 2 MGe 2 S 6 O (M = Zn, Cd) oxysulfides with the GeS 3 O unit show dozens of times improvement in critical birefringence and the NLO effect compared with those of isostructural Sr 2 ZnGe 2 O 7 . Moreover, structure-property study further verifies that the mixed-anion GeS 3 O ligand is a useful NLO-active unit and can offer great influence over the NLO origin. This research result also gives us a feasible design strategy and research system to explore new IR NLO candidates., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A series of M 6 PS 5 X (M = Ag, Cu; X = Cl, Br) nonlinear optical (NLO) chalcohalides with special MS 3 X ligands have been synthesized in this work. Their critical optical performances were systematically measured and the research results show that all of them exhibit strong NLO responses (2.0-2.7 × commercial AgGaS 2 ) and high laser-damage thresholds (1.7-2.3 × AgGaS 2 ), indicating their potential application as good NLO candidates. Furthermore, first-principles calculations were used to study their inherent structure-property relationships and chalcohalides can be expected to be optimal systems for the exploration of new promising IR NLO crystals.

The spectral mismatch between the distribution of sunlight (AM1.5G) and crystalline silicon (c-Si) solar cells is one of the most important limiting factors of the conversion efficiency of photovoltaic (PV) devices. As an effective solution, the use of the luminescence down-shifting (LDS) technique is an important way to improve the short-wavelength response of a solar cell by shifting high-energy photons to the visible range. Herein, a large-area (17 × 17 cm 2 ) luminescent thin film consisting of a ternary europium (Eu 3+ ) complex and polyvinyl alcohol (PVA) was successfully constructed through a solution casting method and further developed as an effective LDS layer to improve the photoelectric conversion efficiency of c-Si solar cells with a large active area (235 cm 2 ). The self-standing LDS layer is flexible, transparent and easily attachable to the surface of the solar cell module. Compared with the uncoated c-Si solar cell, the one coated with the LDS layer displayed an enhancement of ∼15% in external quantum efficiency (EQE) due to the high luminescence quantum yield of the Eu 3+ complex doped inside the layer. These results demonstrate that use of a large area luminescent film embedding an Eu 3+ complex is a versatile and effective strategy to improve the conversion efficiency of large size PV devices, giving rise to its great potential application as an LDS material.