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Effects of pressure on nano- and micro-scale morphological changes in conjugated polymer photovoltaic cells

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Abstract

This paper presents the results of an experimental study of the effects of pressure on polymer chain alignments in poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) blends that are used in bulk heterojunction organic photovoltaic cells (OPVs). The P3HT:PCBM blends on glass were subjected to pressure and annealing at 140 °C. The surface morphologies, nano-/micro-structures and the chain alignments were analyzed using atomic force microscopy techniques and grazing incidence x-ray scattering. The current–voltage characteristics of the resulting devices are also shown to change significantly with changes in the nano-/micro-structures. The polymer chains were aligned in the direction of the applied pressure (edge-on), which reduced the lamellae spacing between the polymer units and increased the degree of crystallinity. The increased crystallinity plays significant role in the current–voltage enhancements. The implications of the study are discussed for the design and control of the nano/microstructures of bulk heterojunction organic solar cells.

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ACKNOWLEDGMENTS

BAT acknowledges the University of Ghana—Carnegie Corporation’s Next Generation of African Academics program (UG-NGAA) for funding. We also appreciate the Nelson Mandela Institution, the African Development Bank, the World Bank STEP-B program, the World Bank African Centers of Excellence program and Rutgers University, USA. Dr Kevin Yager and BNL are acknowledged for the opportunity and assistance at the Synchrotron Facility. We again thank Christopher Petoukhoff, Zeqing Shen and Binxing Yu for the experimental assistance and useful discussions. Appreciations are finally extended to Professor Deidre M. O’Carroll, Professor Eric Garfunkel, and Professor Manish Chowolla for their assistance with the experimental techniques.

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Authors and Affiliations

  1. Department of Materials Science and Engineering, African University of Science and Technology, Abuja, Nigeria

    Benjamin Agyei-Tuffour, Egidius Rutatisbwa Rwenyagila & Winston O. Soboyejo

  2. Department of Materials Science and Engineering, School of Engineering Sciences, University of Ghana, Legon-Accra, Ghana

    Benjamin Agyei-Tuffour

  3. Department of Theoretical and Applied Physics, African University of Science and Technology, Abuja, Nigeria

    Joseph Asare

  4. Department of Materials Science and Engineering, Kwara State University, Ilorin, Kwara State, Nigeria

    Martiale Gaetan Zebaze Kana

  5. Princeton Institute of Materials Technology (PRISM), Department of Mechanical and Aerospace Engineering, Princeton University, New York, New Jersey, USA

    Winston O. Soboyejo

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  1. Benjamin Agyei-Tuffour
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Correspondence to Winston O. Soboyejo.

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Agyei-Tuffour, B., Rwenyagila, E.R., Asare, J. et al. Effects of pressure on nano- and micro-scale morphological changes in conjugated polymer photovoltaic cells. Journal of Materials Research 31, 3187–3195 (2016). https://doi.org/10.1557/jmr.2016.344

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