Browsing by Author "Nikhil, P.P."

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Butterfly-Shaped Thiophene-Pyridine Hybrids: Green Electroluminescence and Large Third-Order Optical Nonlinearities
(Wiley-VCH Verlag info@wiley-vch.de, 2020) Kakekochi, V.; Gangadharappa, S.C.; Nikhil, P.P.; Chandrasekharan, K.; Darshan, V.; Narayanan Unni, K.N.; Udayakumar, U.K.
A set of four symmetric, butterfly-shaped 4-(4-(decyloxy)phenyl)-2,6-di(thiophen-2-yl)pyridine (TPY) derivatives 2TPA-TPY (TPY center and triphenylamine end groups), 2CBZ-TPY (TPY center and N-ethyl carbazole end groups), 2TPY-TPA (triphenylamine center and TPY at the periphery) and 2TPY-CBZ (N-ethyl carbazole center and TPY at the periphery) was synthesized. The molecules show reverse saturable absorption (RSA) which is consistent with two-photon absorption (2PA) associated with excited-state absorption (ESA) when excited using a 532 nm laser beam. The molecules 2TPA-TPY and 2TPY-TPA possess extremely low limiting thresholds of 1.73 and 2.68 J cm?2, respectively. An organic light-emitting diode (OLED) fabricated from 2TPA-TPY exhibits green emission with a maximum luminance of 207 cd m?2, a current efficiency (?CE) of 1.51cd A?1, a maximum power efficiency (?Pmax) of 0.46 lm W?1 and an external quantum efficiency (?EQE) of 0.48 % at 100 cd m?2. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Effects of substituents on the enrichment of the optical limiting action of novel imidazo[2,1-: B] [1,3,4]thiadiazole fused thiophene-based small molecules
(2019) Kakekochi, V.; Udayakumar, D.; Nikhil, P.P.; Chandrasekharan, K.
The imidazo[2,1-b][1,3,4]thiadiazole (ITD) ring is a fused, planar aromatic heterocyclic system consisting of four heteroatoms with a bridgehead nitrogen atom. In this study, three new donor-acceptor-donor (D-A-D)-type organic molecules (ThITD1-ThITD3) were designed and synthesized, wherein ITD was an electron acceptor unit and the thiophene/phenyl moieties were electron donor units that produced a D-A-D configuration. The thiophene-ITD core structure comprises three different groups viz., thiophene-2-acetonitrile (ThITD1), phenylacetonitrile (ThITD2) and rhodanine-3-acetic acid (ThITD3), and the effect of substituents on the optical and electrochemical properties have been discussed based on structural modifications. The third-order nonlinear optical (NLO) properties analyzed by the Z-scan technique reveal that the molecules exhibit effective two photon absorption (TPA) with ThITD3 possessing substantially higher effective TPA coefficient (?eff) than ThITD1 and ThITD2, which is comparable to the reported ?eff values. The results unravel that ITD as an acceptor with an appropriate ?-linker will be a promising candidate for application in the field of optoelectronics/photonics. Herein, the thiophene-ITD ring system was explored for NLO applications and reported for the first time. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Effects of substituents on the enrichment of the optical limiting action of novel imidazo[2,1-: B] [1,3,4]thiadiazole fused thiophene-based small molecules
(Royal Society of Chemistry, 2019) Kakekochi, V.; Udayakumar, D.; Nikhil, P.P.; Chandrasekharan, K.
The imidazo[2,1-b][1,3,4]thiadiazole (ITD) ring is a fused, planar aromatic heterocyclic system consisting of four heteroatoms with a bridgehead nitrogen atom. In this study, three new donor-acceptor-donor (D-A-D)-type organic molecules (ThITD1-ThITD3) were designed and synthesized, wherein ITD was an electron acceptor unit and the thiophene/phenyl moieties were electron donor units that produced a D-A-D configuration. The thiophene-ITD core structure comprises three different groups viz., thiophene-2-acetonitrile (ThITD1), phenylacetonitrile (ThITD2) and rhodanine-3-acetic acid (ThITD3), and the effect of substituents on the optical and electrochemical properties have been discussed based on structural modifications. The third-order nonlinear optical (NLO) properties analyzed by the Z-scan technique reveal that the molecules exhibit effective two photon absorption (TPA) with ThITD3 possessing substantially higher effective TPA coefficient (?eff) than ThITD1 and ThITD2, which is comparable to the reported ?eff values. The results unravel that ITD as an acceptor with an appropriate ?-linker will be a promising candidate for application in the field of optoelectronics/photonics. Herein, the thiophene-ITD ring system was explored for NLO applications and reported for the first time. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Facile synthesis and exploration of excited state assisted two-photon absorption properties of D-A-D type thiophene-pyridine derivatives
(Royal Society of Chemistry, 2020) Kakekochi, V.; Chatnahalli Gangadharappa, S.; Nikhil, P.P.; Chandrasekharan, K.; Wolcan, E.; Udayakumar, U.K.
A series of trigonal-shaped molecules (TPyT and TPyP) and a polymer (P2TPy) with donor-acceptor-donor (D-A-D) structural arrangement were designed with thiophene and 2,4,6-trisubstituted pyridine as the backbone i.e., a 4-(4-(decyloxy)phenyl)-2,6-di(thiophen-2-yl)pyridine core structure, for the first time and synthesized via a microwave assisted one pot reaction. The extension of conjugation of the system by substituting thiophene acrylonitrile (TPyT) and phenyl acrylonitriles (TPyP and P2TPy) via low cost condensation reactions improved the linear optical, electronic and thermal properties of the synthesized compounds. Furthermore, the nonlinear absorption (NLA) was also enriched appreciably by increasing the conjugation. The three compounds showed an "effective two-photon absorption" phenomenon with the NLA coefficient (?eff) of the order of 10-10 m W-1. The suitability to be utilized in the fabrication of all-optical limiting devices is best achieved by polymer P2TPy as it exhibits substantially higher ?eff (7.02 × 10-10 m W-1) and an extremely low optical limiting threshold (1.42 J cm-2). © 2020 The Royal Society of Chemistry and Owner Societies.