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 similar to 1 mu 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 eta=1.1%. Photoresponse up to 1 mu m has been observed with external quantum efficiencies exceeding 15% in the 700-900 nm region. (c) 2006 American Institute of Physics.