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Design and synthesis of new low band gap organic semiconductors for photovoltaic applications

Murali, MG and Dalimba, Udaya Kumar (2014) Design and synthesis of new low band gap organic semiconductors for photovoltaic applications. In: Annual Conference on Oxide-Based Materials and Devices V held at SPIE Photonics West, FEB 02-05, 2014, San Francisco, CA.

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Official URL: http://dx.doi.org/10.1117/12.2045655


Donor-acceptor (D-A) conjugated polymers have attracted a good deal of attention in recent years. In D-A systems, the introduction of electron withdrawing groups reduces E-g by lowering the LUMO levels whereas, the introduction of electron donating groups reduces E-g by raising the HOMO levels. Also, conjugated polymers with desired HOMO and LUMO energy levels could be obtained by the proper selection of donor and acceptor units. Because of this reason, D-A conjugated polymers are emerging as promising materials particularly for polymer light emitting diodes (PLEDs) and polymer solar cells (PSCs). We report the design and synthesis of four new narrow band gap donor-acceptor (D-A) conjugated polymers, PTCNN, PTCNF, PTCNV and PTCNO, containing electron donating 3,4-didodecyloxythiophene and electron accepting cyanovinylene units. The effects of further addition of electron donating and electron withdrawing groups to the repeating unit of a D-A conjugated polymer (PTCNN) on its optical and electrochemical properties are discussed. The studies revealed that the nature of D and A units as well as the extent of alternate D-A structure influences the optical and the electrochemical properties of the polymers. All the polymers are thermally stable up to a temperature of 300 degrees C under nitrogen atmosphere. The electrochemical studies revealed that the polymers possess low-lying HOMO energy levels and low-lying LUMO energy levels. In the UV-Vis absorption study, the polymer films displayed broad absorption in the wavelength region of 400-700 nm. The polymers exhibited low optical band gaps in the range 1.70 - 1.77 eV.

Item Type: Conference Proceedings
Series.: Proceedings of SPIE
Additional Information: Copyright for this article belongs to the SPIE-INT SOC OPTICAL ENGINEERING, 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA
Keywords: Conjugated polymers; Narrow band gap; Cyclic voltammetry; Polymer solar cells; Polymer light-emitting diodes
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 25 Jul 2014 04:39
Last Modified: 25 Jul 2014 04:39
URI: http://eprints.iisc.ac.in/id/eprint/49522

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