| While electronic devices based on organic materials have an increasing presence in display, lighting, and photovoltaic applications, sensor applications have been relatively unexplored. Organic semiconductors offer unique properties which make them particularly desirable for sensing and imaging, and which are impossible or difficult to realize in inorganic semiconductors. This work focuses on developing novel organic-based devices that function as imaging tools, including integrated surface plasmon-emitting devices, active organic devices integrated with scanning probe cantilevers, and tunable organic photodetectors. The fundamental physical mechanisms for excitonic energy coupling in thin film heterostructures, which enable the operation of these devices, are discussed in detail.;Lower refractive index of organic compounds provides several electrical and optical advantages for device design, including large binding energy of excitons and relatively long lifetimes, which can facilitate efficiently coupling of exciton energy to surface plasmons at a nearby metal interface. This thesis describes how to utilize the strong excitonic energy coupling to surface plasmons in thin-film organic optoelectronic devices to transfer energy across a thick metal film, from electrically pumped molecular excitons on one side to molecular excitons on the opposite side. The observed exciton transfer mechanism can be applied to, for example, a solid-state electrically-pumped sensor with nanoscale resolution, or multi-modal imaging of nanomaterials and biological systems. Surface plasmon resonances in electrically-pumped devices can potentially be engineered to create sensitive biochemical reaction detectors, based on the inherent electrical sensitivity of the devices to the exciton decay rate (which in turn responds to nearby chemical species).;In order to increase the spatial resolution of organic-based imaging devices, the fabrication of organic LEDs and organic photodetectors of submicron size on the tips of scanning probe cantilevers is described. The small working area is defined by focused ion beam milling, and the devices are used for simultaneous high-resolution optical imaging and topography measurements.;An organic photodetector with spectral response tunable across the visible spectrum is demonstrated by means of engineering the optical microcavity within the device. Such mechanically flexible and tunable photodetectors are expected to find applications in microfluidics and portable sensing devices, as well as colorimeters. |
