New light harvesting organic conjugated polymers(CP) containing 4,8-bis(2-ethylhexyloxy)benzo[1,2-b;3,4-b]dithiophene(BDT) donor groups and thiophene(T) acceptor groups with various electron-withdrawing groups have garnered great interest for their high power conversion efficiencies (PCE). One of the leading organic light harvesting CP, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7), has shown exceptionally high PCE making it an appealing material for solar cell applications. Herein, we investigated new polymers with BDT donor groups and with thiophene acceptor groups with various electron-withdrawing groups using ultrafast spectroscopy in order to elucidate the spectroscopic and optical properties that contribute to high PCE light harvesting organic CPs. The results show polymers with large dipole moments, large two-photon cross-sections, fast decay dynamics, and low quantum yields exhibited the best PCEs. These properties may be useful in designing more efficient light harvesting CPs.

Ultrafast spectroscopic study of donor-acceptor light-harvesting organic conjugated polymers

251st National Meeting (2016)

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