Low-band gap poly(di-2-thienylthienopyrazine):fullerene solar cells

Two side-chain substituted poly(di-2-thienylthienopyrazine)s (PBEHTT and PTBEHT) are used as electron donor together with phenyl - C 61 butyric acid methyl ester (PCBM) as an electron acceptor in low-band gap bulk heterojunction polymer solar cells. These low-band gap polymers absorb light up to ∼ 1 μ m . Under simulated AM1.5 conditions PTBEHT:PCBM devices provide a short circuit current of J sc = 3.5 mA ∕ cm 2 , an open circuit voltage of V oc = 0.56 V , and a power conversion efficiency of η = 1.1 % . Photoresponse up to 1 μ m has been observed with external quantum efficiencies exceeding 15% in the 700 - 900 nm region.