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Toward High Efficiency Polymer Solar Cells: Influence of Local Chemical Environment and Morphology
Author(s) -
Zhou Cheng,
Zhang Guichuan,
Zhong Chengmei,
Jia Xiaoe,
Luo Peng,
Xu Rongguo,
Gao Ke,
Jiang Xiaofang,
Liu Feng,
Russell Thomas P.,
Huang Fei,
Cao Yong
Publication year - 2017
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201601081
Subject(s) - materials science , polymer solar cell , energy conversion efficiency , polymer , side chain , thiophene , stacking , chemical engineering , conjugated system , morphology (biology) , dipole , chemical structure , open circuit voltage , organic solar cell , chemical physics , nanotechnology , polymer chemistry , optoelectronics , organic chemistry , voltage , composite material , chemistry , physics , quantum mechanics , biology , engineering , genetics
The chemical structure of conjugated polymers plays an important role in determining their physical properties that, in turn, dictates their performance in photovoltaic devices. 5‐Fluoro‐2,1,3‐benzothiadiazole, an asymmetric unit, is incorporated into a thiophene‐based polymer backbone to generate a hole conducting polymers with controlled regioregularity. A high dipole moment is seen in regioregular polymers, which have a tighter interchain stacking that promotes the formation of a morphology in bulk heterojunction blends with improved power conversion efficiencies. Aliphatic side chain substitution is systematically varied to understand the influence of side chain length and symmetry on the morphology and resultant performance. This side chain modification is found to influence crystal orientation and the phase separated morphology. Using the asymmetric side chain substitution with regioregularity of the main chain, an optimized power conversion efficiency of 9.06% is achieved, with an open circuit voltage of 0.72 V, a short circuit current of 19.63 mA cm −2 , and a fill factor over 65%. These results demonstrate that the local chemical environment can dramatically influence the physical properties of the resultant material.