Singlet exciton fission in solution.

Singlet exciton fission, the spin-conserving process that produces two triplet excited states from one photoexcited singlet state, is a means to circumvent the Shockley-Queisser limit in single-junction solar cells. Although the process through which singlet fission occurs is not well characterized, some local order is thought to be necessary for intermolecular coupling. Here, we report a triplet yield of 200% and triplet formation rates approaching the diffusion limit in solutions of bis(triisopropylsilylethynyl (TIPS)) pentacene. We observe a transient bound excimer intermediate, formed by the collision of one photoexcited and one ground-state TIPS-pentacene molecule. The intermediate breaks up when the two triplets separate to each TIPS-pentacene molecule. This efficient system is a model for future singlet-fission materials and for disordered device components that produce cascades of excited states from sunlight.B.J.W. was supported by a Herchel Smith Research Fellowship. A.J.M. received funding from a Marie Curie Scholarship. D.B. is a FNRS Research Director. Both A.J.M and D.B. acknowledge support from the European Community’s Initial Training Network SUPERIOR (PITN-GA-2009-238177). Further funding for this project came from the Engineering and Physical Sciences Research Council (EPSRC) and a pump-prime grant from the Winton Programme for the Physics of Sustainability.This is the accepted version of an article originally published in Nature Chemistry 5, 1019–1024 and available online at http://www.nature.com/nchem/journal/v5/n12/full/nchem.1801.html. Nature Publishing Group's conditions for reuse are detailed at http://www.nature.com/authors/policies/license.html

Compatibility of plasma-deposited linalyl acetate thin films with organic electronic device fabrication techniques

Contact angle and temperature-dependent variable angle spectroscopic ellipsometry measurements have been performed on plasma-deposited linalyl acetate thin films in order to provide insight into the compatibility of the material with current organic electronic fabrication techniques. XPS data on several substrates confirmed that the chemical properties of the thin films were substrate independent. The plasma-deposited layers were found to be insoluble in many solvents commonly used in the deposition of organic semiconducting layers, including chloroform and dichlorobenzene, and the wetting envelope for the surfaces presented. Thermal degradation was found to begin at ~200 °C, and up until this temperature the material's thickness, refractive index and transparency in the visible region were constant. The exhibited properties show plasma-deposited linalyl acetate thin films to be compatible with state of the art organic electronic processing techniques

Plant-derived cis-β-ocimene as a precursor for biocompatible, transparent, thermally-stable dielectric and encapsulating layers for organic electronics

This article presents low-temperature, one-step dry synthesis of optically transparent thermally-stable, biocompatible cis−β−ocimene-based thin films for applications as interlayer dielectric and encapsulating layer for flexible electronic devices, e.g. OLEDs. Morphological analysis of thin films shows uniform, very smooth (R(q) < 1 nm) and defect-free moderately hydrophilic surfaces. The films are optically transparent, with a refractive index of ~1.58 at 600 nm, an optical band gap of ~2.85 eV, and dielectric constant of 3.5−3.6 at 1 kHz. Upon heating, thin films are chemically and optically stable up to at least 200 °C, where thermal stability increases for films manufactured at higher RF power as well as for films deposited away from the plasma glow. Heating of the sample increases the dielectric constant, from 3.7 (25 °C) to 4.7 (120 °C) at 1 kHz for polymer fabricated at 25 W. Polymers are biocompatible with non-adherent THP–1 cells and adherent mouse macrophage cells, including LPS-stimulated macrophages, and maintain their material properties after 48 h of immersion into simulated body fluid. The versatile nature of the films fabricated in this study may be exploited in next-generation consumer electronics and energy technologies