The role of spin in the degradation of organic photovoltaics

Publikation: Beitrag in FachzeitschriftForschungsartikelBeigetragenBegutachtung


  • Ivan Ramirez - , Heliatek GmbH (Autor:in)
  • Alberto Privitera - , University of Oxford (Autor:in)
  • Safakath Karuthedath - , King Abdullah University of Science and Technology (Autor:in)
  • Anna Jungbluth - , University of Oxford (Autor:in)
  • Johannes Benduhn - , Professur für Optoelektronik (Autor:in)
  • Andreas Sperlich - , Julius-Maximilians-Universität Würzburg (Autor:in)
  • Donato Spoltore - , Professur für Optoelektronik (Autor:in)
  • Koen Vandewal - , Stiftungsprofessur für Organische Photovoltaik (Autor:in)
  • Frédéric Laquai - , King Abdullah University of Science and Technology (Autor:in)
  • Moritz Riede - (Autor:in)


Stability is now a critical factor in the commercialization of organic photovoltaic (OPV) devices. Both extrinsic stability to oxygen and water and intrinsic stability to light and heat in inert conditions must be achieved. Triplet states are known to be problematic in both cases, leading to singlet oxygen production or fullerene dimerization. The latter is thought to proceed from unquenched singlet excitons that have undergone intersystem crossing (ISC). Instead, we show that in bulk heterojunction (BHJ) solar cells the photo-degradation of C60 via photo-oligomerization occurs primarily via back-hole transfer (BHT) from a charge-transfer state to a C60 excited triplet state. We demonstrate this to be the principal pathway from a combination of steady-state optoelectronic measurements, time-resolved electron paramagnetic resonance, and temperature-dependent transient absorption spectroscopy on model systems. BHT is a much more serious concern than ISC because it cannot be mitigated by improved exciton quenching, obtained for example by a finer BHJ morphology. As BHT is not specific to fullerenes, our results suggest that the role of electron and hole back transfer in the degradation of BHJs should also be carefully considered when designing stable OPV devices.


FachzeitschriftNature communications
PublikationsstatusVeröffentlicht - Dez. 2021

Externe IDs

PubMed 33473110