Multistep Electron Injection Dynamics and Optical Nonlinearity Investigations of π-Extended Thioalkyl-Substituted Tetrathiafulvalene Sensitizers

Abstract

A comprehensive investigation is presented on the photophysical and third-order nonlinear optical (NLO) properties of two thioalkyl-substituted tetrathiafulvalene molecules (referred here as G1 and G3) to understand their utility as photosensitizers for dyesensitized solar cell (DSSC) and optoelectronic applications. Both steady-state and time-resolved (in the fs−ns time regime) absorption and photoluminescence (PL) spectroscopy techniques were employed to comprehend the excited-state properties of the molecules in solution as well as in thin films deposited on both quartz and mesoporous TiO 2 layers. The spectroscopy measurements in solution and thin films deposited on quartz provided the excited-state properties of dye molecules. Time-resolved PL measurements at the dye−TiO 2 interface provided initial evidence of electron injection by fast PL quenching decay dynamics for both the molecules. Detailed target analysis of the femtosecond transient absorption spectroscopy (TAS) data of the dye−TiO 2 sample revealed a multistep ultrafast electron injection for both molecules with the fastest injection component being 374 and 314 fs for G1 and G3 molecules, respectively. The ultrafast NLO properties of G1 and G3 were studied using the Z-scan technique with 800 nm, ∼70 fs laser pulses. The open aperture measurements showed three-photon absorption with magnitudes of coefficients 4.7 × 10 −5 cm 3 /GW 2 and 5.2 × 10 −5 cm 3 /GW 2 , and the closed aperture measurements provided second hyperpolarizability (γ) values of 3.5 × 10 −31 esu and 4.2 × 10 −31 esu for G1 and G3, respectively. Additionally, the onset of optical limiting was estimated to be 5.8 × 10 −3 J/cm 2 and 5.7 × 10 −3 J/cm 2 for G1 and G3 molecules, respectively.

Ultrafast Nonlinear Optical and Structure–Property Relationship Studies of Pyridine-Based Anthracene Chalcones Using Z-Scan, Degenerate Four-Wave Mixing, and Computational Approaches

“…65 Biswas et al have recently studied the optical nonlinearities of thioalkyl-substituted tetrathiafulvalene molecules by 70 fs and reported n 2 and χ (3) values at 800 nm as 6.8 × 10 −16 cm 2 /W and 3.4 × 10 −14 esu, respectively. 66 3.9.2. 2PA Cross-Sections.…”

Ultrafast Excited State Relaxation Dynamics of New Fuchsine‐ a Triphenylmethane Derivative Dye

“…The complete details of the experimental setup are reported in our earlier publications. [60,61] Briefly, the source pulses from the femtosecond amplifier were split into two beams using a beam-splitter. One of them was focused into a 3-mm thick sapphire window to produce white light continuum from 420 nm to 750 nm, which was used as probe beam.…”

“…The transient data reported here were analyzed using a global and target analysis technique using the least number of components estimated from the singular value decomposition (SVD) of the data matrix performed in "Surface Xplorer" and "Glotaran v. 1.5.1" software. [61][62][63]…”

Optical, Electrochemical, Third-Order Nonlinear Optical Investigations of 3,4,5-Trimethoxy Phenyl Substituted Non-Aqueous Phthalocyanines

“…In the current era of optoelectronics, nonlinear optics (NLO) and related technologies play a significant role in its evolution ( Dini et al, 2016 ; Gounden et al, 2020 ; Mrinalini et al, 2021 ). To revive the study of the potential of NLO in the field of telecommunication, photonics, biomedicine, and optical signal processing, several NLO moieties were designed through various π-conjugated organic molecules ( Mardar, 2006 ; Bures et al, 2012 ; Sofiani et al, 2016 ; Biswas et al, 2020 ). For this reason, a great variety of small organic molecules and macrocyclic systems, such as porphyrins ( Rao et al, 2000 ; Senge et al, 2007 ; Swain et al, 2014a ; Katturi et al, 2020b ; Rathi et al, 2020 ; Vijisha et al, 2020 ; Kumar et al, 2021a ), phthalocyanines ( de la Torre et al, 2004 ; Kumar et al, 2007 ; Swain et al, 2014b ; Zhang et al, 2014 ; Bharati et al, 2018 ; Venkatram et al, 2018a; Venkatram et al, 2018b; Bhattacharya et al, 2019a ; Bhattacharya et al, 2019b ; Bhattacharya et al, 2021 ), corroles ( Katturi et al, 2020a ; Lu et al, 2021 ), porphycenes ( Sarma et al, 2011 ; Swain et al, 2012 ; Pati et al, 2020 ), and BODIPY dyes ( Ngoy et al, 2019 ), have been investigated for their NLO properties.…”