Germanium‐ and Silicon‐Substituted Donor–Acceptor Type Copolymers: Effect of the Bridging Heteroatom on Molecular Packing and Photovoltaic Device Performance. Issue 18 (29th July 2014)

• Record Type: Journal Article
• Authors: Kim, Jong Soo; Fei, Zhuping; Wood, Sebastian; James, David T.; Sim, Myungsun; Cho, Kilwon; Heeney, Martin J.; Kim, Ji‐Seon
• Is Part Of: Advanced energy materials. Volume 4:Issue 18(2014)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2014-07-29
• Subjects: Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.201400527
• Languages: English
• ISSNs: 1614-6832

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The effects of heteroatom substitution from a silicon atom to a germanium atom in donor‐acceptor type low band gap copolymers, poly[(4, 4′‐bis(2‐ethylhexyl)dithieno[3, 2‐b:2′, 3′‐d]silole)‐2, 6‐diyl‐alt‐(2, 1, 3‐benzothiadiazole)‐4, 7‐diyl] (PSiBTBT) and poly[(4, 4′‐bis(2‐ethylhexyl)dithieno[3, 2‐b:2′, 3′‐d]germole)‐2, 6‐diyl‐alt‐(2, 1, 3‐benzothiadiazole)‐4, 7‐diyl] (PGeBTBT), are studied. The optoelectronic and charge transport properties of these polymers are investigated with a particular focus on their use for organic photovoltaic (OPV) devices in blends with phenyl‐C₇₀‐butyric acid methyl ester (PC₇₀BM). It is found that the longer C‐Ge bond length, in comparison to C‐Si, modifies the molecular conformation and leads to a more planar chain conformation in PGeBTBT than PSiBTBT. This increase in molecular planarity leads to enhanced crystallinity and an increased preference for a face‐on backbone orientation, thus leading to higher charge carrier mobility in the diode configuration. These results provide important insight into the impact of the heavy atom substitution on the molecular packing and device performance of polymers based on the poly[2, 6‐(4, 4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2, 1‐b;3, 4‐b]‐dithiophene)‐alt‐4, 7‐(2, 1, 3‐benzothiadiazole) (PCPDTBT) backbone.</p> </abstract>