This work covers the research about the structure, property, performance relationship about polymer solar cells (PSCs). First, an efficient synthetic method is developed for creating ladder-type, oligomeric donor monomers with fused benzodithiophene structures. These monomers are copolymerized with fluorinated thieno[3,4-b]thiophene ester to form a series of polymers which were investigated as donor materials in polymer/fullerene solar cells. Photophysical and electrochemical characterizations are used in conjunction with quantum-chemical calculations to identify the interplay of quinoidal and charge transfer character of conjugated copolymers, providing broadly applicable design rules for tuning the excitation character of conjugated copolymers. X-ray diffraction, mobility measurements, and solar cell device characterization are used to analyze neat films and bulk heterojunctions of these copolymers, demonstrating the importance of the spatial symmetry of the structure unit in determining the charge transport characteristics of conjugated copolymers. Second, the influence of polymer polydispersity on the performance of PSCs composed of PTB7 and PC<sub>71</sub>BM as the active layer materials was studied to reveal that polymers exhibiting large polydispersity index (PDI) may contain structural defects that play the role of energy transfer and charge trapping/recombination centers. The results highlighted the importance of controlling PDI of donor polymers for polymer solar cells.

<br />
Roles of quinoidal character, regioregularity, and polydispersity in determining the photovoltaic performance of conjugated copolymers

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

<br /> Roles of quinoidal character, regioregularity, and polydispersity in determining the photovoltaic performance of conjugated copolymers