New quinoxaline containing donor-acceptor type conjugated polymers for organic solar cells

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2018
Karagaçti, Özge
In this study, quinoxaline, benzotriazole and benzodithiophene containing three random donor-acceptor type copolymers were synthesized and their electrochemical, spectroelectrochemical, kinetic and photovoltaic properties were investigated. Quinoxaline demonstrates electron accepting properties due to having imine nitrogens. Also, benzotriazole derivatives with their electron withdrawing imine groups in their structures also lead to exhibit high electron transporting ability. Benzodithiophene derivatives demonstrate electron donor property because the structure of benzene with coherent thiophene gives these polymers high hole mobility. In addition, alkoxyl groups in benzodithiophene derivatives help to increase the solubility of the polymer. Bringing together these three groups yields the conjugated copolymer with broad absorption band in the visible region. This study includes the construction of random copolymers by using quinoxaline derivatives (5,8-dibromo-2,3-di(thiophen-2-yl) quinoxaline, 5,8-dibromo-2,3-diphenylquinoxaline, 10,13-dibromo-8b,14a-dihydrodibenzo(a,c)phenazine) and 2,6-Bis(trimethylstannyl)-4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene and 4,7-dibromo-2-(2-octyldodecyl)-2H-benzo[d][1,2,3]triazole. 1H and 13C-NMR Spectroscopy were used to investigate the structure of monomers and polymers. Produced polymers were utilized as donor material and PC71BM was used as acceptor material in bulk hetero-junction photovoltaic devices. Power conversion efficiencies of solar cell devices with different Polymer: PC71BM ratios (w:w) were measured under AM 1.5 G illumination (100 mW/cm2) and best PCE value was recorded as 2.22 % with 1:4 (w:w) P2: PC71BM blend ratio.

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Citation Formats
Ö. Karagaçti, “New quinoxaline containing donor-acceptor type conjugated polymers for organic solar cells,” M.S. - Master of Science, Middle East Technical University, 2018.