TY - JOUR
T1 - Interplay of Intramolecular Noncovalent Coulomb Interactions for Semicrystalline Photovoltaic Polymers
AU - Uddin, Mohammad Afsar
AU - Lee, Tack Ho
AU - Xu, Shuhao
AU - Park, Song Yi
AU - Kim, Taehyo
AU - Song, Seyeong
AU - Nguyen, Thanh Luan
AU - Ko, Seo Jin
AU - Hwang, Sungu
AU - Kim, Jin Young
AU - Woo, Han Young
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/9/8
Y1 - 2015/9/8
N2 - Four different kinds of photovoltaic polymers were synthesized by controlling the intrachain noncovalent coulomb interactions through the incorporation of alkoxy- or alkylthio-substituted phenylene, 4,7-di(furan-2-yl)benzothiadiazole, and 4,7-di(thiophen-2-yl)benzothiadiazole as a building block. Fine modulation of the interplay of dipole-dipole, H-bond, and chalcogen-chalcogen interactions (O...S, O...H, S...S, S...F, etc.) along the polymeric backbone influenced the chain planarity, interchain organization, film morphology, and electrical and photovoltaic properties significantly. By replacing the alkoxy substituents with alkylthio groups, the torsional angle increased (136-168°) due to the absence of an O...S attractive coulomb interaction (and/or increased S...S steric hindrance), enhancing the amorphous nature with hindered interchain packing. The alkoxy-substituted polymers exhibited nanofibrillar structures, showing strong interlamellar scattering peaks up to (300) with tight face-on π-π stacking in grazing incidence X-ray scattering. The measured carrier mobility of the alkoxy-containing polymers was 1-2 orders of magnitude higher than that of the alkylthio-containing polymers. The incident-light-intensity-dependent photovoltaic characteristics clearly suggested efficient charge generation/extraction with less charge recombination for the alkoxy-containing semicrystalline polymers. The resulting photovoltaic energy conversion efficiency of the PPDT2FBT, PPDF2FBT, PPsDF2FBT, and PPsDT2FBT blended devices with PC70BM was measured to be 8.28%, 5.63%, 5.12%, and 0.55%, respectively. This study suggests an important molecular design guideline for the further optimization of photovoltaic polymers and devices by finely controlling the interplay of the weak noncovalent coulomb interactions.
AB - Four different kinds of photovoltaic polymers were synthesized by controlling the intrachain noncovalent coulomb interactions through the incorporation of alkoxy- or alkylthio-substituted phenylene, 4,7-di(furan-2-yl)benzothiadiazole, and 4,7-di(thiophen-2-yl)benzothiadiazole as a building block. Fine modulation of the interplay of dipole-dipole, H-bond, and chalcogen-chalcogen interactions (O...S, O...H, S...S, S...F, etc.) along the polymeric backbone influenced the chain planarity, interchain organization, film morphology, and electrical and photovoltaic properties significantly. By replacing the alkoxy substituents with alkylthio groups, the torsional angle increased (136-168°) due to the absence of an O...S attractive coulomb interaction (and/or increased S...S steric hindrance), enhancing the amorphous nature with hindered interchain packing. The alkoxy-substituted polymers exhibited nanofibrillar structures, showing strong interlamellar scattering peaks up to (300) with tight face-on π-π stacking in grazing incidence X-ray scattering. The measured carrier mobility of the alkoxy-containing polymers was 1-2 orders of magnitude higher than that of the alkylthio-containing polymers. The incident-light-intensity-dependent photovoltaic characteristics clearly suggested efficient charge generation/extraction with less charge recombination for the alkoxy-containing semicrystalline polymers. The resulting photovoltaic energy conversion efficiency of the PPDT2FBT, PPDF2FBT, PPsDF2FBT, and PPsDT2FBT blended devices with PC70BM was measured to be 8.28%, 5.63%, 5.12%, and 0.55%, respectively. This study suggests an important molecular design guideline for the further optimization of photovoltaic polymers and devices by finely controlling the interplay of the weak noncovalent coulomb interactions.
UR - http://www.scopus.com/inward/record.url?scp=84941077679&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.5b02251
DO - 10.1021/acs.chemmater.5b02251
M3 - Article
AN - SCOPUS:84941077679
SN - 0897-4756
VL - 27
SP - 5997
EP - 6007
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 17
ER -