New DBfA and DfA types of conjugated block copolymer systems were designed, synthesized, and preliminarily studied for potential cost effective, lightweight, flexible, and high efficiency optoelectronic and solar energy conversion applications, where D is an electron rich donor type conjugated polymer block, B is a non-conjugated and flexible aliphatic hydrocarbon bridge chain (containing different number of methylene units), and fA is a fluorinated electron withdrawing acceptor type conjugated polymer block (See Figure 1). Optoelectronic property studies revealed the UV-Vis absorption of the DBfA and DfA are overlaps of individual electronic absorptions of D and fA, while the solution steady state photoluminescence (PL) emission of D was quenched in both DBfA and DfA that could be attributed by the photo induced charge separations. It appears the PL quenching is strongest in DBfA with shortest aliphatic bridge. Weaker PL quenching in DfA (without bridge unit) may be explained by the existence of twist angles between the conjugated chains of D and fA at the junction of DfA. Thin film morphology studies revealed more uniform and nanoscale phase domains of DBfA as compared to D/fA blend. Preliminary solar cell device studies revealed two orders of magnitude increase of photoelectric power conversion efficiency of DBfA versus simple D/fA blends. These results exhibit a viability of potential block copolymer approach toward optoelectronics.

Development and studies of DBfA/DfA block copolymers for optoelectronics

253rd National Meeting (2017)

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