Femtosecond excited-state dynamics and ultrafast nonlinear optical investigations of ethynylthiophene functionalized porphyrin

Biswas, Chinmoy and Soma, Venugopal Rao and Raavi, Sai Santosh Kumar and et al, . (2022) Femtosecond excited-state dynamics and ultrafast nonlinear optical investigations of ethynylthiophene functionalized porphyrin. Optical Materials, 127. pp. 1-11. ISSN 0925-3467

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Abstract

Ethynylthiophene functionalized D-π-A porphyrin (LG5) belongs to a class of porphyrin molecules with proven application in organic solar cell devices. In this report, we present a comprehensive optical and non-linear optical characterization of ethynylthiophene functionalized porphyrin molecule, denoted as LG5. Femtosecond transient absorption (TA) spectroscopy was used to study the ultrafast excited-state properties with 400 nm, 70 fs photoexcitation. Global and target fitting analysis of the obtained TA spectra established a reliable photophysical model of excited state population relaxation and extracted the various rate constants. Considering the good performance of LG5 as a photosensitizer in dye-sensitized solar cells (DSSCs), electron injection studies on LG5 sensitized mesoporous TiO2 were also performed. Both integrated and transient photoluminescence (PL) data for LG5 sensitized TiO2 samples confirms efficient electron injection. The target analysis on TA data of LG5–TiO2 films revealed a multi-step electron injection from different excited energy levels with both ultrafast (≈370 fs) and slow injections times. Additionally, the non-linear optical (NLO) properties of LG5 are studied using the single-beam Z-scan technique upon photoexcitation of 800 nm, 70 fs laser pulses. The open aperture data demonstrated two-photon absorption (2PA), and closed aperture data indicated the presence of positive nonlinear refraction. The calculated values of 2PA cross-section and 3rd order NLO susceptibility were 1723 GM and 1.89 × 10−13 esu (2.64×10−21m2V−2), respectively. © 2022 Elsevier B.V

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IITH Creators:

IITH Creators	ORCiD
Raavi, Sai Santosh Kumar	http://orcid.org/0000-0002-2496-9233

Item Type:

Article

Additional Information:

RSSK acknowledges the financial support of Department of Science and Technology, India for the following projects no’s BRICS/PilotCall2/ IEEE-OSC/2018 (G) and CRG/2019/003197. CB thanks MHRD India, and IIT Hyderabad, India, for financial support. VRS acknowledges the financial support of DRDO, India, through ACRHEM.

Uncontrolled Keywords:

Nonlinear optical materials; Organic materials; Porphyrins; Transient absorption spectroscopy; Ultrafast phenomena

Subjects:

Physics

Divisions:

Department of Physics

Depositing User:

. LibTrainee 2021

Date Deposited:

28 Jun 2022 09:06

Last Modified:

29 Jun 2022 10:31