Decoding the Structure of Benzodithiophene Polymers for High-Efficiency Organic Solar Cells
Journal article, 2025
The performance of organic electronic devices, such as solar cells, depends on understanding and controlling the solid-state microstructure of semiconducting polymers. In this study, a detailed understanding of the aggregate states, solid-state microstructure, and thermotropic behavior of the best-performing family of polymers for solar cells, i.e., benzodithiophene-based semiconducting polymers, is provided. Using D18, PBnDT-FTAZ, and PBDB-T-Cl as model systems, this study reveals a unique solid mesophase, distinct from previously observed polymer mesophases, comprising stacked solid-like and liquid-like layers. This mesophase resembles sanidic structures while also sharing features with columnar mesophases like condis crystals and paracrystals. At a larger length scale, it organizes into nanoscale fibril-like domains, with polymer backbones aligned along the fibril axis, coexisting with amorphous-like glassy regions, reported here for the first time. Notably, high-performance polymers such as D18, D18-Cl, and PM6 contain minimal glassy regions. The thermotropic behavior of this biphasic nanomorphology is also examined, providing insights into how thermal annealing influences polymer structure. Understanding these solid-aggregate states, the microstructure, and the thermal behavior enables a more precise framework for defining structure–function relationships in semiconducting polymers. This will have a significant impact on the entire field of organic electronics, from organic photovoltaics to bioelectronics to wearable electronics.
organic solar cells
semiconducting polymers
polymer structure
mesophases
crystallization
Author
Matteo Sanviti
University of A Coruña
Sara Marina
University of the Basque Country (UPV/EHU)
Xabier Rodriguez-Martínez
University of A Coruña
Jesika Asatryan
University of A Coruña
Valerio Di Lisio
Donostia International Physics Center
Sandra Hultmark
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Junkal Gutierrez
University of the Basque Country (UPV/EHU)
Eduardo Solano
ALBA Synchrotron Light Facility
Jeromy J. Rech
College of Arts & Sciences
Eugenio L. Solla
University of A Coruña
Wei You
College of Arts & Sciences
Agnieszka Tercjak
University of the Basque Country (UPV/EHU)
M. Eugenio Vázquez
Universidade de Santiagode Compostela
Daniele Cangialosi
Spanish National Research Council (CSIC)
Donostia International Physics Center
Christian Müller
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Harald Ade
North Carolina State University
Jaime Martín
University of A Coruña
Advanced Functional Materials
1616-301X (ISSN) 16163028 (eISSN)
Vol. 35 44 2503634High Entropy Acceptor Mixtures for Stable Organic Solar Cells
Swedish Research Council (VR) (2022-02977), 2023-01-01 -- 2026-12-31.
Subject Categories (SSIF 2025)
Condensed Matter Physics
Physical Chemistry
DOI
10.1002/adfm.202503634