Very-low-bandgap metallopolyynes of platinum with a cyclopentadithiophenone ring for organic solar cells absorbing down to the near-infrared spectral region.

Two solution-processable metallopolyynes of platinum functionalized with the electron-deficient 4H-cyclopenta[2,1-b:3,4-b']dithiophen-4-one spacer and their model molecular complexes were synthesized and developed for the applications of polymer solar cells. These metallated polymers possess extremely low bandgaps of 1.44-1.53 eV which extend toward the near-infrared (NIR) range of the solar spectrum, and represent the lowest optical bandgap yet reported for platinum(II) metallopolyynes to date. The structural flexibility, processibility, and good photovoltaic performance make cyclopentadithiophenone-containing polymers prominent candidates for NIR photovoltaic applications.