Synthesis of Main-Chain Polyoxometalate-Containing Hybrid Polymers and Their Applications in Photovoltaic Cells

Abstract

Hexamolybdate clusters have been embedded through covalent bonds into the main chain of poly(phenylene acetylene)s. These hybrid polymers were synthesized by palladium-catalyzed coupling reactions of a diiodo functionalized cluster with a diethynylbenzene derivative or a diethynyl functionalized cluster with a diiodobenzene derivative. These polymers are soluble in organic solvents such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and free-standing films can be spin-coated or cast from solutions. While hybrid monomer 2a exhibits a sharp melting transition at 246 °C, polymers 5a and 5b show glass transitions at 125 and 102 °C, respectively. Cyclovoltammetry studies of the hybrid polymers revealed a reversible reduction wave at 1.19 V versus Ag/Ag+, comparable to those of bifunctionalized imido derivatives of hexamolybdates. These polymers show intense absorption in the visible range but with little fluorescence emissions, indicating efficient fluorescence quenching of the embedded polyoxometalate (POM) cluster on the organic phenylene acetylene units. Simple single-layer photovoltaic (PV) cells with a device configuration of indium−tin oxide (ITO)/polymer/Ca have been fabricated and a power conversion efficiency of 0.15% has been obtained, which is significantly higher than PV cells fabricated with other conjugated polymers in the same device configuration. These results convincingly demonstrate the potential applications of POM-based organic−inorganic hybrids in molecular electronics and photonics.

A NEW LINDQVIST-TYPE HEXAMOLYBDATE CLUSTER FUNCTIONALIZED WITH THE jt-DONOR LIGAND 4-BROMO-2,6-DIMETHYLPHENYLIMIDO: SPECTROSCOPIC, ELECTROCHEMICAL AND STRUCTURAL STUDIES

“…2-, a number of new organoimido-derivatives of hexamolybdate, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] hexatungstate, 20 and pentatu ngstenmolybdate, 21 have been synthesized, spectroscopically characterized and, the majority, structurally authenticated by X-ray diffraction analysis. Very recently, the stability, bonding character, electronic properties, first hyperpolarizabilities of this type of complexes have also been studied by Density Functional Theory (DFT).…”

“…, bromo- 12,18 and iodoareneimido hexamolybdates [7][8][9][10][13][14][15] and iodoareneimido pentatungstenmolybdate 21 seems to be of great importance considering their potential applications as precursors for the synthesis of new organicinorganic hybrids containing additional organic 7,8,10,14,15 or organometallic 13 groups, or two similar clusters linked by an extended π-conjugated organic spacer. [8][9][10]15 These halogenated precursors have successfully been applied for the synthesis of organoimido-hexamolybdates as polymer pendants 5 and main-chain polymers.…”

“…[8][9][10]15 These halogenated precursors have successfully been applied for the synthesis of organoimido-hexamolybdates as polymer pendants 5 and main-chain polymers. 9,15 In this paper we report the synthesis, spectroscopic characterization, electrochemical studies and the X-ray crystal and molecular structure of the new organic-inorganic hybrid bearing the electron-withdrawal bromo group in a remote position: (n-Bu 4 N) 2 …”

Electroactive Benzothiazole Hydrazones and Their [Mo6O19]2− Derivatives: Promising Building Blocks for Conducting Molecular Materials

“…[31] POMs are easily functionalised [32] and their organic derivatives have found applications in the implementation of covalent POM-based materials, [33][34][35][36][37][38] a class of materials that is rapidly expanding. For example, nitrogeneous derivatives have allowed the synthesis of organic-inorganic hybrids with potentially strong dp interactions.…”

Polymer reaction of poly(p-phenylene–ethynylene) by addition of decaborane: modulation of luminescence and heat resistance

“…[11][12][13][14][15][16][17] For example, p-conjugated polymers containing polyhedral oligomeric silsesquioxanes or polyoxometalate have shown high thermal, mechanical, oxidationresistance and electrochemical properties, as well as heat resistance. [18][19][20][21][22][23][24] Recently, we reported the synthesis of novel p-conjugated polymers with an icosahedral carborane cluster in their main chain, their great thermal durability and surprising optical properties, that is, aggregation-induced emission based on the molecular orbital of o-carborane. [25][26][27][28][29][30][31][32] Although the hybridization of p-conjugated polymers with inorganic clusters has given prominent results, the multistep synthesis of monomers containing inorganic clusters would have obstructed a thorough investigation in this field.…”