The effects of metal impurities in poly[(2,5-bis(3-decylthiophen-2-yl)thieno[2,3-b]thiophene] on field-effect transistor properties - Bjorklund, N; Lill, J-O; Rajander, J; Osterbacka, R; Tierney, S; Heeney, M; McCulloch, I; Coelle, M (ORGANIC ELECTRONICS, 2009)