Unravelling Kinetic Loss Mechanisms in All-Polymer Solar Cells

Shahidul Alam^a^,^b, Wejdan Althobaiti^b, Safakath Karuthedath^c, Christopher E. Petoukhoff^b, Amr Dahman^b, Khawla Alkhezaim^b, Oleksandr Matiash^b, José P. Jurado^b, Mariia Ferree^a, Ning Su^d, Jacob Blaskovits^e, Denis Andrienko^e, Vladimir Dyakonov^f, Andreas Sperlich^f, Vojtech Nádaždy^g, Tobin J. Marks^d, Antonio Facchetti^d^,^h, Frédéric Laquai^a^,^b

^aChair of Physical Chemistry and Spectroscopy of Energy Materials, Department of Chemistry, Ludwig Maximilians University Munich, Butenandtstraße 11 (E), D-81377 Munich, Germany

^bKing Abdullah University of Science and Technology (KAUST), KAUST Solar Platform (KSP), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), Thuwal 23955-6900, Kingdom of Saudi Arabia

^cInstitute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055 China

^dDepartment of Chemistry, Center for Light Energy-Activated Redox Processes, and the Materials Re-search Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (USA)

^eMax Planck Institute for Polymer Research (MPIP), Ackermannweg 10, D-55128 Mainz, Germany

^fExperimental Physics 6, Julius-Maximilians-Universität Würzburg, D-97074 Würzburg, Germany

^gInstitute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovak Republic

^hSchool of Materials Science and Engineering, Georgia Institute of Technology; Atlanta, GA 30332, USA

Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV26)

Uppsala, Sweden, 2026 May 18th - 20th

Organizers: Gerrit Boschloo, Ellen Moons, Feng Gao and Anders Hagfeldt

Oral, Shahidul Alam, presentation 117
Publication date: 11th March 2026

All-polymer solar cells offer potential advantages in mechanical robustness and morphological stability, yet they remain less efficient than state-of-the-art small-molecule non-fullerene acceptor–based organic solar cells. In this work, we investigate the efficiency-limiting processes in all-polymer bulk heterojunction devices based on the donor polymers PBDB-T and PBDB-T-2F (PM6) blended with the polymer acceptors PYN-BDT and PYN-BDTF. Owing to π-extended naphthalene units, the acceptor polymers exhibit strong absorption extending to approximately 900 nm. A combination of steady-state spectroscopy and time-resolved techniques—including transient absorption, time-resolved photoluminescence, photoluminescence-detected magnetic resonance, and time-delayed collection field measurements—enables a quantitative analysis of charge-generation and loss processes. Kinetic parameters and process yields derived from pulsed-laser spectroscopy reproduce the measured current–voltage characteristics, confirming the consistency of the approach. The results show that moderate fill factors arise from non-geminate recombination competing with charge extraction and from field-dependent charge generation, with the relative importance of these processes depending on the polymer acceptor. The methodology provides a general framework for quantifying loss mechanisms in bulk heterojunction organic solar cells.

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