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We present a solution-processed pseudo bi-layer organic solar cell with poly(3-hexyl thiophene) (P3HT) as donor and indene-C60 bisadduct (ICBA) as acceptor. The devices were fabricated by sequential processing of the active components followed by a thermal annealing treatment. An efficiency of 5.9% was achieved under AM 1.5G irradiation (1000 W/m2). The obtained efficiency is attributed to an enhanced nanomorphology that arises from the inter-diffusion of the ICBA molecules into a layer of pre-organised polymer (P3HT) and also due to the subsequent crystallisation of the ICBA molecules. These processes facilitate efficient charge generation and extraction. Time of flight-secondary ion mass spectroscopy (TOF-SIMS) depth profiling was carried out for different thermal annealing treatments of these pseudo bi-layer devices, which reveals full inter-diffusion of ICBA into the polymer P3HT. Photo-CELIV (charge extraction by linearly increasing voltage) studies elucidates that the thermal annealing imparts crystallinity to the fullerene phase which results in the improvement of charge carrier mobility.

The copolymers of methacrylic acid with protoporphyrin IX (PPIX) and the metal complexes, zinc protoporphyrin IX and magnesium protoporphyrin IX were synthesised and characterised. Corresponding acrylic acid copolymers were also synthesised. The steady state absorption and fluorescence spectral properties of the macromolecular bound fluorophores PPIX, Zn-PPIX and Mg-PPIX were investigated. Poly(methacrylic acid) bound protoporphyrin IX, zinc protoporphyrin IX and magnesium protoporphyrin IX show an increase in the fluorescence intensity and lifetime with increase in the pH in the range 2-8 with a marked transition around pH 6.0-7.0. The fluorophore concentration in the dilute solution of the copolymers is micromolar and the fluorophore to the carboxylic acid monomer ratios in the copolymer is around 10 -3 . The molecular weight of the copolymers is 100 ± 10 kD. The fluorescence decay curves of all the fluorophore bound polymers follow biexponential decay fit independent of pH. Poly(MAA-co-PPIX) and poly(MAA-co-MgPPIX) undergo well marked pH induced structural transitions in the pH range of 6.0-7.0 whereas poly(MAA-co-ZnPPIX) undergoes pH induced structural transitions in the pH range of 4.0. In the case of polyacrylic acid copolymers the changes observed in the steady state and time resolved fluorescence studies are less marked. The distinct hydrophobic and hydrophilic environments experienced by the fluorophore bound to PMMA are attributed to the dynamics of the macromolecules in dilute aqueous solutions manifested by the α-methyl group present in the copolymer. The studies carried out using the fluorophores in the time windows from 2 ns to 12 ns indicate evolving trends in the dynamic coiling and reverse coiling of poly methacrylic acid chain.

Micrometre-sized mesoporous materials have characteristic grains as well as pores nearly in the same scale. Electrodes of mesoporous materials for lithium batteries have short transport lengths for Li+ ions due to their nano-sized grains (10–20 nm), and easy access for electrolytes due to their nanopores (5–10 nm). Such mesoporous materials have high packing densities unlike nanopowders, nanowires, nanorods and nanotubes. Despite such advantages, electronic conduction over micrometre-sized particles limits the rate performance of mesporous materials. Occasionally counductive thin layers (2–5 nm) of carbon or RuO2 have been used to overcome such kinetic limitations and to achieve high storage performances. In this manuscript, we present a simple approach for the synthesis of mesoporous TiO2 anatase using a soft-template method, which shows superior storage performance without such conductive surface layers. Various cationic surfactants with different chain lengths have been selected for this investigation to assist the formation of the mesoporous TiO2 structure. Among these, cetyl trimethylammoniumbromide templated C16-TiO2 has the highest surface area of 135 m2 g−1 and reversible capacity of 288, 220, 138,134 and 107 mAh g−1 at 0.2, 1, 5, 10 and 30C respectively. The storage performance of the as-synthesized mesoporous TiO2 is nearly five times better than the commercially available TiO2 nanopowder. The packing density of meso-TiO2 is found to be 6.6 times higher than the TiO2 nanopowder. In addition, battery testing using mesoporous TiO2 electrodes without the 15% carbon additive exhibits nearly the same performance at low rate as the meso-TiO2 with carbon additives. These exciting results suggest a facile conduction path for electrons, a unique character of micrometre-sized mesoporous TiO2 with highly interconnected nanograins of 15–20 nm.

The present work demonstrates the usefulness of the soft-template directed approach in preparing mesoporous titanium dioxide and applying it in dye-sensitized solar cells (DSSCs). Mesoporous titanium dioxide with nanograins of dimension in the range, 16-20 nm were prepared through the soft-templating approach using various cationic surfactants such as octyl-, dodecyl-, cetyl trimethylammonium bromide with different surfactant compositions and titania precursor concentrations. As-synthesized mesoporous titanium dioxide samples were characterized by TGA, PXRD, FESEM, HRTEM and surface area measurements, used as photo-electrode material in DSSCs. Under global AM 1.5 solar irradiation, the best photovoltaic performance of 7.5% with a short circuit photocurrent density of 14.2 mA/cm(-2), an open circuit voltage of 748 mV, and a fill factor of 70.83% were obtained for the DSSC using a film of mesoporous TiO2 synthesized from the cetyl trimethylammoniumbromide surfactant. In contrast, the use of commercial titania powder P25 resulted in an efficiency of 5.0% under similar conditions. The structural and morphological merits of these template-directed materials will be especially addressed in comparison with their traditional bulk forms.