Patel, Jessica and Sharma, Abhishek and Chauhan, Mihirsinh and Aatif, Md and Vashistha, Nikita and Kumar, Mahesh and Tripathi, Brijesh and Chand, Suresh and Tiwari, J. P. and Pandey, Manoj Kumar (2019) Understanding charge carrier dynamics in a P3HT:FLR blend. Physical Chemistry Chemical Physics, 21 (5). pp. 2771-2782. ISSN 1463-9076
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Abstract
In organic semiconductors, optical absorption is pivotal for the performance of optoelectronic devices. The absorption by the semiconductors generates excitons which dissociate into free charge carriers, resulting in energy conversion. Although high performance has been achieved in non-fullerene organic solar cells, their charge generation behavior is far from being well understood. Keeping this in view, we have employed optical spectroscopic tools to study the charge generation mechanism in FLR (1,6,7,10-tetramethylfluoranthene) as a non-fullerene electron acceptor blended with P3HT (poly(3-hexylthiophene)) as an electron donor in five different solvents. Through steady state UV-visible and photoluminescence spectroscopy, we provide a basic understanding of charge transport by enlightening the influence of solvents on the aggregation behavior and exciton bandwidth. Furthermore, for the first time, by employing ultrafast vis-NIR transient absorption spectroscopy, we address the ultrafast charge generation and charge separation mechanism with systematic variation in solvent polarity by incorporating the time evolution of the transient species under various pump-probe wavelengths in the range of 450 nm to 1600 nm. For the different excitation wavelengths, the lifetime kinetics have been depicted by their multiexponential fits. The results show a fast decay term at a lifetime of a few picoseconds (ps) (approximate to 1 to 5 ps) and a slow decay term at a lifetime of approximate to 500 ps. The charge generation in the P3HT:FLR blend proceeds on a ps time scale, which implies good intermixing of the components. It is clearly established that the non-halogenated solvents influence this aggregation behavior and higher conjugation lengths with higher photoluminescence quenching contribute to the higher charge generation. The enhanced polaron population in P3HT with the addition of FLR illustrates the importance of this acceptor material in the blend because a good solvent-material combination is essential to enhance the charge generation. As such, this comprehensive study explicitly shows the role of FLR as an emerging efficient non-fullerene acceptor for further improving the performance of devices.
| Item Type: | Article |
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| Additional Information: | Copyright for this article belongs to M/s Royal Society of Chemistry. |
| Subjects: | Chemistry > Physical Chemistry Physics > Atomic and Molecular Physics |
| Divisions: | UNSPECIFIED |
| Depositing User: | Mr. Yogesh Joshi |
| Date Deposited: | 19 Aug 2026 11:35 |
| Last Modified: | 19 Aug 2026 11:35 |
| URI: | https://npl.csircentral.net/id/eprint/4336 |
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