Microphase separated block copolymers provide an opportunity to control the mesoscale structure in the active layer of organic electronic devices.  Donor-acceptor block copolymers have been shown to self-assemble into lamellar morphologies in the active layer, leading to power conversion efficiencies in photovoltaic devices as high as 3% with remarkable open-circuit voltages above 1.2 V.  These materials can also serve as testbeds to address fundamental questions regarding charge photogeneration.  For example, we have explored the role of crystal texturing in microphase-separated active layers on the performance of solar cells.  We have also utilized conjugated block copolymers as model donor-acceptor complexes, allowing us to explore the role of energetics and dielectric constant on the formation of intramolecular charge transfer states using steady state and ultrafast spectroscopy.  Furthermore, coupling a strongly crystallizable block to a weakly crystalline block perturbs crystallization within films; in particular, order within the weakly crystalline phase is enhanced.  As a consequence, electron mobilities higher than either of the homopolymers are extracted using bottom gate, bottom contact transistors with aluminum source and drain contacts and block copolymer active layers.  Thus, our results suggest that block copolymer architectures can be used to enhance charge mobilities in polymer semiconductors and overall performance in organic electronic devices. <br/>

Controlling the active layer microstructure through conjugated block copolymers for solar cells and transistors

253rd National Meeting (2017)

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