The development and study of materials for optoelectronic devices and sensors
Luminescence is a property of materials that allows for the emission of photons when a given amount of energy is applied. The luminescent properties of both polymeric and small molecule materials can generally be controlled through rational design, allowing for the development of materials that can be used in a variety of applications (e.g. sensing, light emissive devices, photovoltaics, photochemistry, etc…). Several families of small molecule emissive materials were designed for use in light emitting electrochemical cells (LEECs). A set of iridium complexes was designed to promote rapid turn-on time in devices, as well as raise the LEEC’s external quantum efficiency (EQE). By systematically substituting mesityl groups onto a base iridium complex, the turn-on times were lowered from minutes to seconds for systems containing the new substituents. Furthermore, the EQE was raised from 0.45% to 1.38% for one material. The study of platinum-based emitters in LEEC devices has not been previously reported, thus it is of interest to determine if this subset of highly efficient emitters may behave in devices similarly to iridium complexes. A family of platinum complexes was synthesized and studies are ongoing to establish device behavior. Moreover, an all organic, ionic set of emissive small molecules was synthesized. Studies are similarly ongoing to determine device behavior. Sensing is also an important capability of some emissive materials. The sensitivity of particular materials to their environment is an attribute that can be utilized to design a sensor. By using a mixed lanthanide metal-organic-framework (MOF), the sensing of trace (<0.5%) water in organics was accomplished. How the systems are able to show such sensitivity was also examined to determine how to further improve upon the MOF’s sensing abilities. This same material was further used in a fingerprinting system that permits the rapid identification of unknown solvents.