(355f) Titanium Oxide Hydrates As Optically and Photonically Versatile Species in Inorganic-Organic Hybrids for Polymer-Based Energy Harvesting and Conversion Devices

Inorganic-organic hybrids allow for the modification of physical properties and the addition of new features in polymer-based systems, and thus have received great interest. For example, the addition of a higher refractive index inorganic species into an organic polymer allows for the increase of the refractive index of the final material beyond that of the indices reached with polymers alone. Most hybrids (or nanocomposites), however, commonly suffer from absorption and/or scattering losses due to the nature and size of the inorganic species. We demonstrate here that titanium oxide hydrates are highly versatile inorganic ‘fillers’ in polymer-based hybrids. Titanium oxide hydrates are typically used as precursors for crystalline TiO₂, a well-known material used in a wide range of applications due to its moderate price, biocompatibility, and efficient photo-catalytic property. Beneficially, using the hydrate also allows for the creation of versatile, low-temperature, sol-gel processed hybrids. We show that these hydrates increase the refractive index of hybrid materials with no or minimal optical loss. Using organic species that contain several hydroxyl moieties appear, thereby, to have a stabilizing effect on the titanium oxide hydrates. Such ‘matrices’ can also create an oxygen barrier to the Ti-species. This oxygen barrier is advantageous for inducing a strong photo-catalytic response of Ti(IV) to Ti(III) in such hybrid films because it limits the re-oxidation of Ti(III) in air. The high transparency in the visible and near-infrared range could also prove useful for producing low-loss photonic structures to aid and improve light management. Because of the solution-processability of the hybrids, such light-management structures promise to be readily implemented in devices such as organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs), providing pathways to increase their overall performance, device efficiency and, potentially, long term stability.