Speaker
Anne Guilbert
(Imperial College London)
Description
Nowadays, the best performing designs of organic solar cell are based on blend films of a conjugated polymer and a fullerene derivative. The best studied example is the blend of poly(3-hexylthiophene-2,5-diyl) (P3HT) as the donor and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor. The performance of such devices is strongly related to the blend microstructure. The best performing systems feature a phase separation of 10 of nanometers. Crystallisation of the polymer donor is known to drive phase separation processes. Therefore, in the selection of new semiconductor materials for improved light harvesting or higher photovoltage, it is essential to understand the effect of the chemical structure on microstructure and to find ways to control it. In this work, we present comnined experimental and simulation studies of two groups of conjugated polymers. In the first study, we use grazing incidence X-ray diffraction and molecular dynamics to study the effect of modifying the structure and attachment of side chains in poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3 ,4-b']dithiophene-2,6-diyl]] (PCPDTBT) and related polymers. It has been observed that either replacing the carbon bridging atom between the backbone and the side chains with a silicon atom or shortening the side chains increases the tendency of the polymer to aggregate, resulting in an increased crystallinity and hole mobility. The second study concerns the side chain dynamics of two conjugated poly-alkyl-thiophenes with different side chain length, P3HT and poly(3-octylthiophene) (P3OT). Here we use quasi-elastic neutron scattering and molecular dynamics to study the effect of side chain structure on the polymer dynamics.
Primary authors
Anne Guilbert
(Imperial College London)
Antonio Urbina
Donal D.C. Bradley
Ellis Pires
(Imperial College London)
J. Emyr Macdonald
Jarvist M. Frost
(Imperial College London)
Jenny Nelson
Tiziano Agostinelli
(Imperial College London)
