Browsing by Author "Narayanan Unni, K.N."

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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