Online Ph.D. Defense: “Dynamics of Charge Carrier Traps in Organic Semiconductors” — March 30, 2021 at 9 AM

Ms. Hamna Iqbal
Mentor:  Professor Oana Jurchescu
Department of Physics
Wake Forest University
Tuesday, March 30, 2021 at 9:00am – 11:00 am
(Private defense will follow public presentation)
Virtual Reception following private defense
Via Video Conference (contact wfuphys@wfu.edu for link information)

ABSTRACT

Organic semiconductors (OSCs) are becoming an integral part of our lives as active components of various optoelectronic devices given their low-cost processing, light weight, chemical versatility by molecular design, and compatibility with flexible substrates. These systems undergo considerable electronic and structural transformations during device fabrication and operation, which can profoundly impact their performance and stability. Characterization techniques that can elucidate the mechanisms of the time-dependent transformations occurring in these materials and devices are needed to guide the design and processing to yield high-performance and stable devices. In this dissertation, a highly efficient method is introduced to elucidate the microscopic processes occurring within OSCs and electronic devices when deliberately exposed to different external stimuli by accessing in real time, the trap density of states (DOS) spectrum of the OSC using organic field-effect transistor (OFET) measurements. In the first study, the method was employed to monitor the generation/annihilation of charge carrier traps in a high-mobility small molecule OSC as a result of microstructural changes occurring in the film during exposure to solvent vapors. Next, we investigate the underlying physical processes impacting the operational stability of OFETs based on small molecules and conjugated polymers. Lastly, we investigate the role of water-related traps in the operation of polymer OFETs. The trap DOS analysis provided an experimental platform to identify several performance limiting processes taking place in OFETs. Consequently, these insights allowed us to devise strategies to consistently achieve high performance devices with exceptional operational and environmental stability.

PUBLICATIONS

1. Iqbal, H. F., Matthew, W., Chen, H, McCulloch, I. and Jurchescu, O. D., “Elucidating the role of water-related traps in the operation of polymer field-effect transistors”, Advanced Functional Materials, Submitted
2. Iqbal, H. F., Ai, Q., Thorley, K. J., Chen, H, McCulloch, I., Risko, C., Anthony, J. E. and Jurchescu, O. D. “Suppressing bias stress degradation in high performance solution processed organic transistors operating in air”, Nature Communications, In Press (2021)
3. Zeidell, A. M., Ren, T., Filston, D. S., Iqbal, H. F., Holland, E., Bourland, J. D., Anthony, J. E., Jurchescu, O. D., Advanced Science, 7, 2001522 (2020)
   • Best Paper Award, South Eastern Chapter of the American Association of Physicists in Medicine (SEAAPM), 2020
4. Zeidell, A. M., Filston, D. S., Waldrip, M., Iqbal, H. F., Chen, H., McCulloch, I., Jurchescu, O. D., Advanced Materials Technologies, 5, 2000390 (2020)
5. Iqbal, H. F., Holland, E. K., Anthony, J. E. and Jurchescu, O. D, Materials Horizons, 7, 2390 – 2398 (2020)
   • Part of a special themed online collection, ‘Horrizons Community Bord Collection: Advanced Memory Technologies’
6. Waldrip, M., Iqbal, H. F., Wadsworth, A., McCulloch, I. and Jurchescu, O. D., Flexible and printed electronics, 5, 014015 (2020)
7. Haneef, H. F., Zeidell, A. M. and Jurchescu, O. D., Journal of Materials Chemistry C, 8, 759 – 787 (2020)
   • Invited Review
   • One of 50 most popular articles of the Journal of Materials Chemistry C in 2020
8. Dasari, R. R., Wang, X., Wiscons, R. A., Haneef, H. F., Ashokan, A., Zhang, Y., Fonari, M. S., Barlow, S., Coropceanu, V., Timofeeva, T. V., Jurchescu, O. D., Brédas, J., Matzger, A. J. and Marder, S. R., Advanced Functional Materials, 29, 1904858 (2019)
9. Petty, A. J., Ai, Q., Sorli, J. C., Haneef, H. F., Purdum, G. E., Boehm, A., Granger, D. B., Gu, K., Rubinger, C. P. L., Parkin, S. R., Graham, K. R., Jurchescu, O. D., Loo, Y., Risko, C. and Anthony, J. E., Chemical Science, 10, 10543 – 10 549 (2019)
10. Rubinger, C. P. L., Haneef, H. F., Hewitt, C., Carroll, D., Anthony, J. E. and Jurchescu, O. D., Organic Electronics, 68, 205 – 211 (2019)
11. Lamport, Z. A., Haneef, H. F., Anand, S., Waldrip, M. and Jurchescu, O. D., Journal of Applied Physics, 124, 071101 (2018)
    • Invited tutorial
12. Pookpanratana, S. J., Goetz, K. P., Bittle, E. G., Haneef, H. F., You, L., Hacker, C. A., Robey, S. W., Jurchescu, O. D., Ovsyannikov and R., Giangrisostomi, E., Organic electronics, 61, 157 – 163 (2018)
13. Zhang, L., Zhou, Y., Guo, L, Zhao, W., Barnes, A., Zhang, H., Eaton, C., Zheng, Y., Brahlek, M., Haneef, H. F., Podraza, N. J., Chan, M. H. W., Gopalan, V., Rabe, K. M. and Engel-Herbert, R., “Correlated metals as transparent conductors”, Nature Materials, 15, 204 (2016)
14. Choi, S. G., Kang, J., Li, J., Haneef, H. F., Podraza, N. J., Beall, C., Wei, S. H., Christensen, S. T. and Repins, I. L., Applied Physics Letters, 106, 043902 (2015)
15. Haneef, H. F. and Podraza, N. J., Journal of Applied Physics, 116, 163507 (2014)

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