Thermally-Induced Degradation in PM6:Y6-Based Bulk Heterojunction Organic Solar Cells

Shahidul Alam*, Haya Aldosari, Christopher E. Petoukhoff, Tomáš Váry, Wejdan Althobaiti, Maryam Alqurashi, Hua Tang, Jafar I. Khan, Vojtech Nádaždy, Peter Müller-Buschbaum, Gregory C. Welch, Frédéric Laquai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Thermally induced degradation of organic photovoltaic devices hinders the commercialization of this emerging PV technology. Thus, a precise understanding of the origin of thermal device instability, as well as identifying strategies to circumvent degradation is of utmost importance. Here, it investigates thermally-induced degradation of state-of-the-art PBDB-T-2F (PM6):BTP (Y6) bulk heterojunction solar cells at different temperatures and reveal changes of their optical properties, photophysics, and morphology. The open-circuit voltage and fill factor of thermally degraded devices are limited by dissociation and charge collection efficiency differences, while the short-circuit current density is only slightly affected. Energy-resolved electrochemical impedance spectroscopy measurements reveal that thermally degraded samples exhibit a higher energy barrier for the charge-transfer state to charge-separated state conversion. Furthermore, the field dependence of charge generation, recombination, and extraction are studied by time-delayed collection field and transient photocurrent and photovoltage experiments, indicating significant bimolecular recombination limits device performance. Finally, coupled optical-electrical device simulations are conducted to fit the devices’ current-voltage characteristics, enabling us to find useful correlations between optical and electrical properties of the active layers and device performance parameters.

Original languageEnglish (US)
Article number2308076
JournalAdvanced Functional Materials
Issue number6
StateAccepted/In press - 2023

Bibliographical note

Publisher Copyright:
© 2023 Wiley-VCH GmbH.


  • bulk-heterojunction
  • charge generation and recombination
  • organic solar cells
  • photophysics
  • thermal degradation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Chemistry
  • Biomaterials
  • General Materials Science
  • Condensed Matter Physics
  • Electrochemistry


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