Introduction All conjugated block copolymer (BCP) systems have been shown to exhibit unique self assembly properties that can produce well ordered bulk heterojunctions or photovoltaic (PV) devices. It has been shown in that covalently linked donor-acceptor systems composed of P3HT and fullerene derivatives can act as a compatibilizer and drive self assembly of P3HT/C60 to enhance PV performance.1 P3HT-C60 BCP have shown to also function as a single component PV device at 11% acceptor block ratio that allows for enhanced morphological control and morphological stability.2 In this work, varying block ratios of donor and acceptor components were synthesized and studied to demonstrate the control over morphological and physical properties. By controlling the block ratios we demonstrate the influence of these physical components that contribute to PV performance. Experimental Synthesis. P3HT-C60 block copolymers were synthesized according to Chan et al using GRIM metathesis of 2,5-dibromo-3-hexylthiophene and 2,5-dibromo-6-bromo-3-hexylthiophene. By altering the monomer feed ratios we were able to control the polymer block ratio components. Subsequent post-polymerization reactions were used to attach C60 to the functionalized hexyl-chain.1a Characterization. Polymers were characterized through 1H NMR, gel permeation chromatography, digital scanning calorimetry, and cyclic voltammetry. Thin Films. P3HT-C60 BCP was dissolved in dichlorobenzene and spin coated on substrates to examine PV performance, surface roughness with atomic force microscopy (AFM), confocal fluorescence measurements. Conclusions Through the control of donor-acceptor block ratios we demonstrate the influence over C60 loading on morphology of the BCP in thin films and their effects on PV performance and allow the achievement of optimization of efficiency. References 1. (a) Chan, S.-H.; Lai, C.-S.; Chen, H.-L.; Ting, C.; Chen, C.-P., Highly Efficient P3HT: C60 Solar Cell Free of Annealing Process. Macromolecules 2011, 44 (22), 8886-8891; (b) Lee, J. U.; Jung, J. W.; Emrick, T.; Russell, T. P.; Jo, W. H., Synthesis of C60-end capped P3HT and its application for high performance of P3HT/PCBM bulk heterojunction solar cells. Journal of Materials Chemistry 2010, 20 (16), 3287-3294. 2. Miyanishi, S.; Zhang, Y.; Tajima, K.; Hashimoto, K., Fullerene attached all-semiconducting diblock copolymers for stable single-component polymer solar cells. Chemical Communications 2010, 46 (36), 6723-6725.

Ratio Influence on morphological and physical properties of P3HT-C60 all-conjugated block copolymer systems

249th National Meeting (2015)

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