Self-Assembled Semiconducting Block Copolymers for Efficient Photonic Devices

The performance of organic light emitting diodes (OLED) and photovoltaic devices (PV) devices depends on the transport of charges for recombination (or charge separation) and hence performance relies critically on the morphology of the active layer. Ideally, interfaces between electron-donating and electron-accepting components must be patterned on the exciton diffusion length scale, 10nm: a length scale accessible via block copolymer self-assembly. We synthesize a rod-coil block copolymer via the condensation of electron-transporting electron-donor, poly(phenylene vinylidene) (PPV), and poly(methyl acrylate), which is later functionalized with a hole-transporting electron-acceptor, carbazole. The resulting block copolymer self-assembles both on the 10 nm length scale associated with block copolymer microphase separation and on the much smaller scale associated with the liquid crystallinity of the PPV. The relationships between the self-assembled morphology and the device performance of OLEDs and PVs will be discussed.