Presenter(s): Madelyn Scott—Chemistry, Physics
Faculty Mentor(s): Kelly Wilson, Cathy Wong
Session 2: Cells R Us
Organic semiconducting materials are appealing, green alternatives to conventional semiconductors because they can be solution-processed into flexible films . However, solution-processing fabrication methods can be prone to morphological disorder, meaning that crystalline structures in the
film exhibit a variety of sizes and shapes . A large degree of morphological disorder inhibits the electronic functionality of a film for use in technological devices . Examining how film morphology varies with different deposition conditions allows us to connect the physical properties of organic semiconducting films to macroscopic perturbations in their formation environments . In this work, we used a homebuilt microscope to image the polarization-dependent absorption of organic films, and developed an image analysis software package to characterize their spatial morphology . A series of pictures are collected of the sample, rotating the polarizer between each image . For every pixel in the image, the absorption signal as a function of polarization angle is fit to a sinusoidal curve . These fits are employed to assign pixels in the image to discrete aggregate domains within the film . Quantitative domain metrics are computed to describe the morphology of the film . Several organic films are produced under different deposition conditions and their resulting morphologies are compared . By better understanding the relationship between deposition conditions and film formation, existing solution-processing techniques can be further controlled and refined to achieve target physical properties in organic semiconducting materials .