Neutron Scattering Series

CFM Seminars

Speaker

Antonio Urbina
Public University of Navarra

When

2026/03/03
11:00

Place

CFM Auditorium

Host

Neutron Scattering Seminars Committee

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What can neutron scattering reveal about the structure and dynamics of organic solar cells?

Organic solar cells, in which a donor and an acceptor mixture creates the so-called “bulk-heterojunction” (BHJ)  optoelectronic active layer, are very promising devices for sustainable photovoltaics [1]. This active layer is mainly fabricated with a conjugated polymer (acting as donor) and small molecules or nanoparticles (acting as acceptors). Poly-[3-hexylthiophene] (P3HT) has been the benchmark donor in bulk-heterojunction organic solar cells (OSCs), and new derivatives of poly-thiophenes have driven a large interest in new approaches for polymeric solar cells with non-fullerene acceptors, for example P5TCN-Fx with cyano-group substitutions and varied fluorination degrees delivered high efficient OSCs [2], and more recently a 20% power conversion efficiency was achieved in polymeric OSCs in which a dual fibrillar molecular structure with a thiophene terminated non-fullerene acceptor, L8-ThCl, was used to induce the fibrillization of both polymer donor and host acceptor polymers [3]. The interplay between structure and dynamics of the materials (at nanometer spatial interpenetration scale, and picosecond time scale) is critical to understand the photocurrent generation mechanism. In this seminar, I will present the results obtained by characterization of conjugated polymers by:  i) small angle neutron scattering, which shows an interesting reversible gelification process demonstrating that the fibrillar structure is triggered in solution, ii) quasielastic neutron scattering that explores the temperature dependence of the dynamics of P3HT at several time scales [4], and iii) the vertical composition reorganization upon annealing of the active layer explored by neutron reflectometry [5].

References:

[1] A. Urbina, Sustainable Solar Electricity, 1st ed., Springer International Publishing, 2022. https://link.springer.com/book/10.1007/978-3-030-91771-5

[2] X. Yuan, Y. Zhao, D. Xie, L. Pan, X. Liu, C. Duan, F. Huang, Y. Cao, Polythiophenes for organic solar cells with efficiency surpassing 17%, Joule 6 (2022) 647–661. https://doi.org/10.1016/j.joule.2022.02.006

[3] C. Chen, L. Wang, W. Xia, K. Qiu, C. Guo, Z. Gan, J. Zhou, Y. Sun, D. Liu, W. Li, T. Wang, Molecular interaction induced dual fibrils towards organic solar cells with certified efficiency over 20%, Nature Communications 15 (2024) 6865. https://doi.org/10.1038/s41467-024-51359-w

[4] A.A.Y. Guilbert, A. Urbina, J. Abad, C. Diaz-Paniagua, F. Batallan, T. Seydel, M. Zbiri, V. Garcia-Sakai, J. Nelson, Temperature-Dependent Dynamics of Polyalkylthiophene Conjugated Polymers: A Combined Neutron Scattering and Simulation Study, Chemistry of Materials 27 (2015) 7652–7661. https://doi.org/10.1021/acs.chemmater.5b03001

[5] A. Urbina, J. Abad, A.J. Fernandez Romero, J.S. Lacasa, J. Colchero, J.F. Gonzalez-Martinez, J. Rubio-Zuazo, G.R. Castro, P. Gutfreund, Neutron reflectometry and hard X-ray photoelectron spectroscopy study of the vertical segregation of PCBM in organic solar cells, Solar Energy Materials and Solar Cells 191 (2019) 62–70. https://doi.org/10.1016/j.solmat.2018.10.004