Tunable light-harvesting polymers containing embedded dipolar chromophores for polymer solar cell applications

A series of light-harvesting conjugated polymers were designed and synthesized for polymer solar cells. These newly designed polymers comprise an unusual two-dimensional conjugated structure with an electron-rich thiophene-triphenylamine backbone and stable planar indacenodithiophene π-bridges terminated with tunable electron acceptors. It was found that the electron-withdrawing strength of the acceptor could be used to manipulate the energy level of the lowest unoccupied molecular orbital and bandgap (as much as 0.3 eV), generating derivatives with complementary absorbance in the visible spectrum. This approach provides great flexibility in fine tuning the electronic and optical properties of the resultant polymers and facilitates the investigation of how these chemical modifications alter the subsequent photovoltaic properties of these materials. © 2012 Wiley Periodicals, Inc.