Date of Award
8-2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
Committee Chair/Advisor
Dr. Jason McNeill
Committee Member
Dr. Dvora Perahia
Committee Member
Dr. David Jacobson
Committee Member
Dr. Jeffrey Anker
Committee Member
Dr. Brain Dominy
Abstract
Understanding how charge carrier move through conjugated polymers is crucial for optimizing the functionality and efficiency of various applications, from organic solar cells and light-emitting diodes (LEDs) to field-effect transistors. Previous studies have demonstrated that tracking the fluorescence centroid displacement provides a method to determine the position of single charge carriers in a conjugated polymer nanoparticle. This method allows the observation of charge carrier trajectories over time and allow researchers to obtain insights into the dynamic processes. In addition, a detailed map of the energy landscape can be constructed by analyzing the fluorescence spectrum. These techniques were previously applied to conjugated polymer nanoparticles comprising dozens or hundreds of polymer chains. In this dissertation, we aim to apply this charge carrier tracking technique to individual isolated conjugated polymer chain. This approach is expected to yield a more detailed chain segment level picture of charge transport and the energy landscape of conjugated polymers. We observe distinctive behaviors where polarons hop repeatly between specific red-emitting sites. The mobility range and spatial heterogeneity of trapping sites were characterized through analysis of position trajectories and autocorrelation functions,. The distribution of hopping times, approximating a normal distribution, indicates that single polymer chains exhibit more homogeneous properties compared to PFBT nanoparticles. By applying the Arrhenius equation to the polaron hopping time constants, we estimated the energy barrier heights for polaron motion in the range from 520 to 600 meV, with the distribution width of these barriers suggesting greater structural uniformity compared to typical amorphous polymer films. This approach provides researchers a valuable method to gain the detailed insight in charge carrier dynamics and structural information of conjugated polymers which are helpful in guiding the development and optimization of polymer-based devices for electronic and optoelectronic applications.
Recommended Citation
Lei, Ming, "Single Charge Carrier Dynamics in a Single Polymer Chain" (2024). All Dissertations. 3688.
https://open.clemson.edu/all_dissertations/3688