Photovoltaic properties of Thiophene-based polymers and synthesis of polymeric materials containing Tri- or Hexa-nuclear Platinum clusters as structural components

Polymer photovoltaics have a great technological potential as an alternative source for electrical energy. The demand for inexpensive, renewable energy sources is the driving force for new approaches in the production of low-band-gap polymers. We report chemical and electrochemical synthesis of new copolymer, poly(3BrTh-co- 3HTh). Photovoltaic properties of devices prepared from chemically synthesized poly[3-(6-bromohexyl)thiophene] and newly electrochemically synthesized copolymer were studied, and compared with standard devices based on poly(3-hexylthiophene). Bulk- and bilayer-heterojunction photovoltaic devices were fabricated by spin-coating and layer-by-layer electrochemical deposition technique and their characterization are described in this dissertation. The introduction of metal cluster into a polymeric structure can dramatically change its metal content, when the polynuclear moieties are present in every repeat unit or pendent to the main chain. So the resulting new kind of material represents an excellent potential for the preparation of processable, functional materials with intriguing properties. So apart from the synthesis and characterization of Bi- and Bulkheterojunction photovoltaic devices this thesis deals with the synthesis, spectral characterization of thiophene-based polymers containing 44e− trinuclear cluster [Pt3(μ−PBut2)3(CO)3](CF3SO3) (7) and 82e− hexanuclear cluster [Pt6(μ−PBut2)4(CO)6](CF3SO3)2 (9) in the side- and main-chain. The synthesis, electrochemical characterization and possibility of electropolymerization of Platinum tri- and hexa-nuclear cluster containing thiophene-based monomers were also discussed. The trinuclear cluster (7) and hexanuclear cluster (9), both were prepared from the triangular precursor Pt3(μ−PBut 2)3(CO)2H (6). The hexanuclear cluster (9) contains a tetrahedral core of four platinum atoms with the opposite edges bridged by other two (“apical”) platinum centres, and four bridging di-t-butylphosphido ligands. The coordination of the platinum metal atoms is completed by six CO-ligands bonded to each platinum centre. Fortunately, the two carbonyl groups bonded to the apical platinum centres are easily substituted or attacked by nucleophiles than the inner four, which are bonded to the Pt4 tetrahedron. In case of triangular cluster (7) the t-butyl substituents hinder and stabilize the central Pt3P3 core, leaving only three reactive positions, mutually directed at 120° and localized on the Pt3P3 plane, available for the functionalization of the cluster unit. The extension of the knowledge on the general reactivity of the trinuclear and hexanuclear precursors, together with the synthesis and characterization of simple polymeric materials and oligomers achieved in this work, and these polymers could be useful for photovoltaic application in future. A templating strategy based on polystyrene colloidal self-assembly has been demonstrated for electrochemical fabrication of poly(3BrTh-co-3HTh) inverse opal as an donor layer in the fabrication of photovoltaic devices, and the morphology of highly ordered, two-dimensional opal structure was revealed by means of AFM observation. The fabrication approach could be extended for the direct electrochemical polymerization of metal or metal cluster containing monomers on the surface of polystyrene colloid deposited Indium tin oxide coated glass substrate.