Synthesis of a New Conjugated Polymer Composed of Pyrene and Bithiophene Units for Organic Solar Cells

초록

An alternating conjugated copolymer composed of pyrene and bithiophene units, poly(DHBT-alt-PYR) has been synthesized. The synthesized polymer was found to exhibit good solution processibility and thermal stability, losing less than 5% of their weight on heating to approximately 370 degrees C. The synthesized polymer showed its maximum absorption and peak PL emission at 401 and 548 nm, respectively. The optical band gap energy of the polymer was determined by absorption onset to be 2.64 eV. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the polymer was determined to be -5.48 and -2.84 eV by cyclic voltametry (CV) and the optical band gap. The polymer photovoltaic devices were fabricated with a typical sandwich structure of ITO/PEDOT:PSS/active layer/LiF/Al using poly(DHBT-alt-PYR) as an electron donor and C(60)-PCBM or C(70)-PCBM as electron acceptors. The open circuit voltage, short circuit current and fill factor of the device using C(70)-PCBM as an acceptor were 0.75 V, 3.80 mA/cm(2) and 0.28, respectively, and the maximum power conversion efficiency of the device was 0.80%.

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