Presenter(s): Madelyn Scott − Chemistry
Faculty Mentor(s): Cathy Wong, Kelly Wilson
Poster 15
Research Area: Physical Chemistry
Funding: Community for Minorities in STEM (CMiS) Travel Award Scholarship; Phil and Penny Knight Campus for Accelerating Scientific Impact
Organic semiconductors offer a green alternative to conventional conductive materials because they can be solution- processed on an industrial scale for use in solar cells and OLEDs. The electronic transitions in organic semiconducting materials determine their charge-carrying efficiency for use in such devices. Transient absorption spectroscopy can be used to track the population of mobile electron-hole pair combinations at controlled delay times after photogeneration by a laser pulse. This technique is typically used to study equilibrated systems, like static solutions or films, but not materials as they evolve. For in situ studies of non-equilibrated systems, the Wong Lab has developed a single-shot transient absorption (ssTA) spectrometer to measure the excited state dynamics of thin films during deposition by a capillary or slot die coater. The solution capillary is two microscope slides spaced by aluminum shims and housed in an aluminum frame. The slot die coater is an apparatus designed to mimic solution-processed films that are manufactured roll-to-roll on an industrial scale. In both deposition techniques, a mechanical slide pusher is attached to the deposition device and positioned over an aluminum
stage to produce films on microscope slides. Experimental parameters considered during optimization of each deposition method included the following: slide pusher velocity, cleaning methods of the deposition slides, temperature of the depositing solution, and materials constructing the slide pusher apparatus. It was determined that the slot die coater enables more control over film quality than the solution capillary, producing films with more homogenous solution coverage. As a result, the slot die coater will be incorporated into the spectroscopy apparatus for the first in situ ssTA measurements of non- equilibrated material systems.