Although fluid lipid films have been used widely in biosensing devices, they lack the high stability desired for technological implementation because the noncovalent forces between the constituent lipids are relatively weak. In this work, polymerized, planar supported lipid bilayers ((poly)PSLBs) composed of diene-functionalized lipids have been prepared and characterized. Several parameters relating (poly)-PSLB structure and stability to observations made in studies of polymerized bilayer vesicles were examined, including a comparison of UV photopolymerization and redox-initiated radical polymerization, the number and location of the polymerizable moieties in the lipid monomer, and a comparison to PSLBs produced with diacetylene lipids. Redox-initiated polymerization of films composed of bis-substituted diene lipids with at least one polymerizable moiety located near the acyl terminus produced dried PSLBs that were highly uniform and stable. All other conditions yielded PSLBs that contained a high density of defects after drying, including those formed from diacetylene lipids. In most cases, defect formation is attributed to desorption of unreacted monomers or low molecular weight polymers when the film was passed through the air/water interface. Studies on highly stable (poly)PSLBs doped with nonpolymerizable lipids showed that 40-80% of the dopants are retained when the film is dried. Thus to ensure quantitative lipid retention upon PSLB removal from water, all of the lipid monomers must be covalently anchored to the polymer network.
Planar supported lipid bilayers (PSLBs) composed of phosphorylcholine (PC) lipids are known to be highly resistant to nonspecific adsorption of soluble proteins. However, these structures lack the stability desired for implementation in molecular devices (e.g., biosensors).
Recent developments in solution processable single junction polymer solar cells have led to a significant improvement in power conversion efficiencies from ∼5% to beyond 9%. While much of the initial efficiency improvements were driven through judicious design of donor polymers, it is the engineering of device architectures through the incorporation of inorganic nanostructures and better processing that has continued the efficiency gains. Inorganic nano-components such as carbon nanotubes, graphene and its derivatives, metal nanoparticles and metal oxides have played a central role in improving device performance and longevity beyond those achieved by conventional 3G polymer solar cells. The present work aims to summarise the diverse roles played by the nanosystems and features in state of the art next generation (4G) polymer solar cells. The challenges associated with the engineering of such devices for future deployment are also discussed.
The optical properties of thin films of poly[p-(2,5-didodecylphenylene)ethynylene] (DPPE)
have been investigated. In chloroform solution the DPPE exhibit structured blue emission with a lifetime
of 0.4 ns. In contrast to the solution, pristine DPPE films show a broad featureless green fluorescence
with a nonexponential decay with time constants of 1.15 ns (8%) and 5.9 ns (92%). Upon annealing, the
emission spectrum returns to a structured blue emission similar to the solution, and the fluorescence
decay is nonexponential with a component at 0.45 ns (38%) and 90 ps (62%). Both spin-cast and annealed
films possess similar absorption spectra, suggesting that the lifetime difference is due to an excimer-like
state in the pristine film and efficient fluorescence from isolated chains within the annealed films. The
decrease of the fluorescence lifetime from 0.4 ns (DPPE in solution) to 90 ps (annealed DPPE films) is
further attributed to the lack of conformational disorder found within the ordered solid state.
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