Synthesis of Thieno[3,4-b]pyrazine-based Alternating Conjugated Polymers via Direct Arylation for Near-infrared OLED Applications

Three alternating conjugated polymers,namely PFTP,PCzTP,and PSiTP,which combine a thieno[3,4-b]pyrazine (TP) unit with different benzene-based donor units such as 9,9-dioctylfluorene,9-heptadecyl-gH-carbazole and 5,5-dioctyl-5H-dibenzo[b,d]silole,were synthesized in good yield (＞85％) and high molecular weight up to Mn=5.82×104 via direct arylation polymerization (DArP).All the resultant polymers exhibit moderate bandgap of about 1.80 eV and strong deep red/near-infrared emitting in the solid state.Among them,the PSiTP-based electroluminescence (EL) devices with an architecture of ITO/PEDOT:PSS/PTAA/emitting layer/TPBi/LiF/Al give the best performance with a maximum luminance of 2543 cd/m2 at 478 mA/cm2.This work expands the application scope of high-performance conjugated polymers which can be synthesized by DArP.