Date of Award

Fall 10-2022

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Polymer Science and Engineering

Committee Chair

Jason D. Azoulay

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Xiaodan Gu

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Sarah E. Morgan

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Derek L. Patton

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Yoan Simon

Committee Member 5 School

Polymer Science and Engineering


Infrared (IR) photodetection (0.9–15 μm) has many appealing applications in imaging, telecommunications, sensing, defense, and more. The current state-of-the-art IR photodetectors are commonly based on inherently rigid inorganic semiconductors that require complex manufacturing, are costly, and impose low-temperature cooling requirements for satisfactory operation. Therefore, photodetectors based on organic semiconductors have been broadly investigated, benefitting from chemical tunability, solution processability, and ease of fabrication processes. This dissertation explores several synthesized novel narrow bandgap donor-acceptor conjugated polymers and their utility in solution-processable devices comprising bulk heterojunction (BHJ) photodiodes and monolithic photoconductor architectures.

Chapter I briefly summarizes donor-acceptor conjugated polymers, where precise control of their structural and electronic properties affords materials with narrow bandgaps to enable absorption spanning the infrared. Next, the fundamental concepts and mechanisms behind the photodiode and photoconductor devices are introduced in addition to the performance metrics of photodetectors. Chapter II establishes the experimental protocols and methods for extracting material properties and device performance parameters. Chapter III entails a screening study of various novel narrow bandgap polymers to assess their initial performance in devices. Selected polymers were further studied on the effect of side chain variants and high boiling point additives on the morphology that affects the performance of the photodetector. In materials that displayed even narrower bandgaps (< 0.5 eV), the photoconductor configuration was used to mitigate the limitations of using a BHJ. Chapter IV addresses the challenges in increasing iii dark noise under bias associated with narrow bandgap systems, followed by introducing the use of high bandgap insulators to suppress the noise. Finally, Chapter V provides a conclusion and suggested future work in the IR photodetectors.

Available for download on Thursday, October 17, 2047