Insight into the relationship between the Ionization Energy (IE) offsets between donor and acceptor materials and the performance of the organic solar cells (OSC) could improve the charge generation efficiency. Charge generation can proceed through two different paths in Bulk Heterojunction (BHJ) based OSCs which are electron transfer from donor to acceptor and hole transfer from acceptor to donor. Electron transfer can be controlled by electron affinities and hole transfer can be controlled by ionization energies. In this work, large IE offsets were investigated in poly(3-hexylthiophene-2,5-diyl)(P3HT):Non Fullerene Acceptor (NFA) based OSCs by fabricating and characterizing devices, also conducting several experiments to optimize the processing conditions for the devices. These results provide an overview of the charge transfer and IE offsets dependence, also a general picture of the photophysics in P3HT:NFAs based OSCs. Moreover, using wide bandgap polymer donor which has shallow IE such as P3HT with low-bandgap NFAs may provide sufficient IE offsets between donor and acceptors enabled us to reach the inverted Marcus regime. In this regime, the electron transfer rate decreases upon decreasing the charge transfer (CT) state energy compared to the exciton energy. The decrease of the internal quantum efficiency (IQE) upon increasing the IE offset suggests that we are in that regime.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/670709 |
| Date | 03 July 2021 |
| Creators | Althobaiti, Wejdan |
| Contributors | Laquai, Frédéric, Physical Science and Engineering (PSE) Division, Anthopoulos, Thomas D., McCulloch, Iain |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | 2022-08-22, At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis will become available to the public after the expiration of the embargo on 2022-08-22. |
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