Description

This fellowship opportunity at the National Institute of Standards and Technology (NIST) focuses on investigating how the primary chemical structure, formulation, and processing of organic semiconductors influence their spatially resolved microstructure development. The research targets recently developed polymer semiconductors exhibiting transistor performance comparable to amorphous silicon.

Organic semiconductors are notable for their solubility in common solvents, enabling low-cost, printed fabrication methods for devices such as transistors, solar cells, and sensors. However, the microstructure of these materials evolves dynamically during solution drying, influenced by deposition methods, solvents, drying rates, and substrate properties. The resulting nanoscale polycrystalline films exhibit microstructure variations from sub-nanometer to millimeter scales, which critically affect device performance.

The research will employ advanced measurement tools including electron microscopies, selective area diffraction, and scanning probe techniques to study nucleation and growth mechanisms, grain boundary characteristics, and interface behavior with dielectrics and conductors. These spatially resolved measurements will complement whole-film characterization methods like grazing-incidence x-ray diffraction and polarized photon absorption spectroscopies. Ultimately, correlating microstructure with transistor characteristics such as carrier mobility aims to guide the rational design of next-generation organic semiconductor materials and processing techniques.