High performance all-polymer photodetector comprising a donor-Acceptor-Acceptor structured indacenodithiophene-bithieno[3,4-c] pyrroletetrone copolymer

The synthesis of an acceptor polymer PIDT-2TPD, comprising indacenodithiophene (IDT) as the electron-rich unit and an interconnected bithieno[3,4-c]pyrrole-4,4′,6,6′-Tetrone (2TPD) as the electron-deficient unit, and its application for all-polymer photodetectors is reported. The optical, electrochemical, charge transport, and device properties of a blend of poly(3-hexylthiophene) and PIDT-2TPD are studied. The blend shows strong complementary absorption and balanced electron and hole mobility, which are desired properties for a photoactive layer. The device exhibits dark current density in the order of 10 ^-5 mA/cm ² , external quantum efficiency broadly above 30%, and nearly planar detectivity over the entire visible spectral range (maximum of 1.1 × 10 ¹² Jones at 610 nm) under-5 V bias. These results indicate that PIDT-2TPD is a highly functional new type of acceptor and further motivate the use of 2TPD as a building block for other n-Type materials.