Visible tunable lighting system based on polymer composites embedding ZnO and metallic clusters: from colloids to thin films

Abstract

The development of phosphor devices free of heavy metal or rare earth elements is an important issue for environmental reasons and energy efficiency. Different mixtures of ZnO nanocrystals with Cs2Mo6I8(OOC2F5)6 cluster compound (CMIF) dispersed into polyvinylpyrrolidone matrix have been prepared by very simple and low cost solution chemistry. The resulting solutions have been used to fabricate highly transparent and luminescent films by dip coating free of heavy metal or rare earth elements. The luminescence properties of solution and dip-coated films were investigated. The luminescence of such a system is strongly dependent on the ratios between ZnO and CMIF amounts, the excitation wavelength and the nature of the system. By varying these two parameters (ratio and wavelength), a large variety of colors, from blue to red as well as white, can be achieved. In addition, differences in the luminescence properties have been observed between solutions and thin films as well as changes of CMIF emission band maximum wavelength. This may suggest some possible interactions between the different luminophore centers, such as energy transfer or ligands exchange on the Mo6 clusters.

Mo6 cluster-based compounds for energy conversion applications: comparative study of photoluminescence and cathodoluminescence

“…Thus, a large variety of Mo 6 -based MCs have been investigated for potential applications in lighting [6,9–11], solar cells [12–14], and biotechnologies [15–19]. Additionally, their high chemical flexibility has already allowed the fabrication of transparent nanocomposite thin films in organic or inorganic matrices that can be easily coated on substrates for photonic applications [20,21] Moreover, in addition to their very interesting optical properties for energy conversion applications (molecule-like energy gaps, strong photoluminescence in near infrared (NIR) region, etc. ), they have also some specific electronic and electrochemical properties with strong potential for energy storage and supply applications (superconductivity, battery, thermoelectricity, hydrogen affinity, etc.)…”

From Cs2Mo6Cl14 to Cs2Mo6Cl14·H2O and Vice Versa: Crystal Chemistry Investigations

“…Face-capped Mo 6 X i 8 X a 6 units containing octahedral molybdenum clusters are the basic buildings blocks of many inorganic solid state compounds, hybrid frameworks and nanomaterials [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Formation of Mo 6 cluster occurs at high temperatures via solid state reactions.…”

“…Different routes to prepare Cs 2 Mo 6 X i 8 X a 6 (X = Cl, Br and I) have been reported in literature: (i) solid state synthesis at high temperature from mixture of MoX 2 and CsX [14,27], (ii) synthesis from MoX 2 solution, AX salts and HX solution [28], and (iii) synthesis from a derivative method reported by Flemström et al [29] using ðH 3 O) 2 Mo 6 X i 8 X a 6 Á 7H 2 O solution [30] and AX salts. Preparation of highly pure Cs 2 Mo 6 X i 8 X a 6 sample in high yield requires purification of the product by dissolution, filtration, and evaporation process.…”

Luminescent coordination polymers based on Ca2+ and octahedral cluster anions [{M6Cli8}Cla6]2− (M = Mo, W): synthesis and thermal stability studies

“…Indeed, depending on X and L, some members of this family demonstrate intensive luminescence in the red/near-infrared region with emission lifetimes of hundreds of microseconds and often with significant quantum yields. [11][12][13][14][15][16][17] Due to these properties, materials based on these clusters have been demonstrated to have potential in solar energy harvesting, 18,19 bioimaging, photodynamic therapy, [20][21][22] photo-catalysis, [23][24][25][26][27] oxygen sensing, [28][29][30][31] lighting, [32][33][34] etc.…”