Sequencing functional conjugated polymers by high resolution SPM imaging

Session

Stream 4 (AFM): SPM Techniques on Energy Materials and Processes

Authors

Prof Giovanni Costantini (1)

Affiliations

1. University of Warwick

Keywords

STM, conjugated polymers, microstructure, sequence, electrospray deposition

Abstract text

In this talk I will demonstrate that high resolution scanning probe microscopy is capable of delivering crucial information — that cannot be achieved by any other current analytical method — about “real world” energy materials with a huge practical and technological relevance. In particular, I will show that by combining vacuum electrospray deposition (ESD) and high-resolution scanning tunnelling microscopy (STM) it is possible to image conjugated polymers used in organic electronics and photovoltaic devices with unprecedented detail. 

Based on this, it becomes possible to sequence the polymers by visual inspection and to determine their molecular mass distribution by simply counting the repeat units. Moreover, I will demonstrate that we can precisely determine the nature, locate the position, and ascertain the number of defects in the polymer backbone.^1-3 The analysis of our high-resolution images univocally demonstrates that one of the main drivers for backbone conformation and polymer self-assembly is the maximization of alkyl side-chain interdigitation. On this basis, we investigate the 2D assembly of a series of conjugated polymers with the aim of gaining insight in the molecular microsctructure of the corresponding 3D functional thin films.^4,5

High-resolution STM image of (a) poly(C₁₄DPPF-F), (b) pBTTT, and (c) IDT-BT on Au(111).

References

1.  D.A. Warr, L.M.A. Perdigão, H. Pinfold, J. Blohm, D. Stringer, A. Leventis, H. Bronstein, A. Troisi, G. Costantini, Sequencing conjugated polymers by eye, Sci. Adv. 4, eaas9543 (2018).

2.   M. Xiao, B. Kang, S.B. Lee, L.M.A. Perdigão, A.M.T. Luci, S.P. Senanaya, M. Nikolka, M. Statz, Y. Wu, A. Sadhanala, S. Schott, R. Carey, Q. Wang, M. Lee, C. Kim, A. Onwubiko, C. Jellett, H. Liao, W. Yue, K. Cho, G. Costantini, I. McCulloch, and H. Sirringhaus, Anisotropy of charge transport in a uniaxially aligned fused electron deficient polymer by solution shear coating, Adv. Mater. 32, 2000063 (2020).

3.   S.S. Lawton, D.A. Warr, L. M. A. Perdigão, Y. Changa, A. Pron, G. Costantini, and D.M. Haddleton, Determining the sequence and backbone structure of 'semi-statistical' copolymers as donor-acceptor polymers in organic solar cells, Sustain. Energy Fuels 4, 2026 (2020).

4.   H. Chen, A. Wadsworth, C. Ma, A. Nanni, W. Zhang, M. Nikolka, A.M.T. Luci, L.M.A. Perdigão, K.J. Thorley, C. Cendra, B. Larson, G. Rumbles, T.D. Anthopoulos, A. Salleo, G. Costantini, H. Sirringhaus, and I. McCulloch, The Effect of Backbone Extension in Thienobenzo[b]indacenodithiophene Polymers for Organic Field-Effect Transistors, J. Am. Chem. Soc. 141, 18806 (2019).

5.   D.A. Warr, et al., in preparation.

References