High efficiency polymer solar cells based on alkylthio substituted benzothiadiazole-quaterthiophene alternating conjugated polymers

Article abstract of DOI:10.1016/j.orgel.2016.10.032

We have designed and synthesized two alkylthio substituted benzothiadiazole-quaterthiophene based conjugated polymers (P1 and P2) and investigated their photovoltaic performances. Theoretical simulation has demonstrated that the introduction of alkylthio substituents can increase the planarity of the resulted conjugated polymers. The fluorinated polymer P1 possesses a deeper HOMO energy level than the non-fluorinated polymer P2 and can form well-developed fibril networks when blended with PC₇₁BM. PSCs based on P1:PC₇₁BM (1:1.2, by weight) gave a PCE of 7.76% with a V_oc of 0.69?V, a J_sc of 16.30?mA?cm^?2 and an FF of 0.69. Our results have demonstrated that alkylthiothiophene could be a useful building block for the construction of high efficiency polymer donor materials used for PSCs.