Near-field Scanning Optical Microscopy (NSOM) has demonstrated sub-wavelength spatial resolution and has been applied to a broad range of systems. However, a combination of illumination geometry, absorption losses in the tip, and photobleaching in purely optical NSOM techniques results in low signal-to-noise ratios, severe tip heating, sample degradation, and unpredictable response. A different means of localized, on-demand photon generation is needed to further improve the measurement.
The proposed research addresses these challenges by studying the effects of nanometer scale confinement of charges and excitons in organic semiconductors. A multifunctional scanning nano-probe tool will be fabricated, consisting of an electrically pumped organic light emitting diode (OLED) deposited inside of a nanoscale cylindrical cavity in the vertex of a scanning probe cantilever.
Intellectual Merit: The proposed nano-OLED probe will be 100 times smaller than individually addressable OLEDs made to date, providing a powerful platform for investigating surface interactions that influence the performance of other nano-scale devices. This will result in greater understanding of the fundamental mechanisms and scaling laws of charge and energy transport in functional organic materials. This will in turn enable improvements in the performance characteristics of large-area organic optoelectronic devices. The ability to electrically pump the probe will allow the study of sensitive biological materials, photonic devices, and materials. The proposed research will also examine fundamental issues of molecular transport in highly confined geometries, as well as organic deposition techniques having broader applications in nano-fabrication.
Broader Impact: As a new NSOM technique with electrical pumping and tunability, the nano-OLED probe can become the optical equivalent of STM, enabling new applications such as a read-write head for nanoscale optical bit storage elements and tunable nanosensor arrays. Studying the confinement of light and charge carriers, as well as nanofabrication using organic materials, can impact the development of electrically pumped organic lasers, and the integration of tunable light sources and sensors with nano-scale electronic circuits. The nano-OLED probe will enhance research and education infrastructure by providing novel instrumentation for the study of nanosystems. Through its interdisciplinary nature, this project will train students in the emerging fields of organic electronics and nano-fabrication. The research results will be integrated into the curricula of at least two departments, promoting teaching and training that will enable further and collaborative studies in the state-of-the-art nanoscale characterization and processing tools.
