Syntheses and optical, electrochemical, and photovoltaic properties of polymers with 6?(2?thienyl)?4H?thieno[2,3?b]indole with a variety of electron?deficient units

ABSTRACTConjugated polymers were synthesized and used for polymer solar cells with new electron?rich units, 6?(2?thienyl)?4H?thieno[2,3?b]indole (2?TTI). 2?TTI was coupled with electron?pulling units, including benzothiadiazole and benzimidazole derivatives, to provide push–pull types of conjugated polymers (poly(8?(heptadecan?9?yl)?6?(thiophen?2?yl)?8H?thieno[2,3?b]indole)?alt?(2?methyl?5,6?bis(octyloxy)?4,7?di(thiophen?2?yl)?2?(trifluoromethyl)?2H?benzimidazole) (PTTIDOCF3), poly(8?(heptadecan?9?yl)?6?(thiophen?2?yl)?8H?thieno[2,3?b]indole)?alt?(5,6?bis(octyloxy)?4,7?di(thiophen?2?yl)?2,1,3?benzothiadiazole) (PTTIDOBT), poly(8?(heptadecan?9?yl)?6?(thiophen?2?yl)?8H?thieno[2,3?b]indole)?alt?(2,2?dimethyl?4,7?di(thiophen?2?yl)?2H?benzimidazole) (PTTIMBI), and poly(8?(heptadecan?9?yl)?6?(thiophen?2?yl)?8H?thieno[2,3?b]indole)?alt?(2,2?dimethyl?5,6?bis(octyloxy)?4,7?di(thiophen?2?yl)?2H?benzimidazole) (PTTIDOMBI)). The synthesized conjugated polymers provided deep highest occupied molecular orbital energy levels for higher open?circuit voltages (VOC). The device composed of PTTIDOMBI and [6,6]?Phenyl C71 butyric acid methyl ester PC71BM (1:2) with chloronaphthalene additive showed a VOC of 0.72 V, a short?circuit current (JSC) of 9.16 mA/cm2, and a fill factor of 0.43; this gave a power conversion efficiency (PCE) of 2.84%. The PTTIDOMBI provided better morphology for enhanced charge transport, and this led to the higher JSC and PCE of the organic solar cells. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47624.

» Author: Juae Kim, Sangmin Chae, Ahra Yi, Seungyeon Hong, Hyo Jung Kim, Hongsuk Suh

» Reference: doi:10.1002/app.47624

» Publication Date: 18/02/2019

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