Unraveling the Impact of Solution Filtration on Organic Solar Cell Stability

Despite major advances in efficiency, the operational stability of organic photovoltaic (OPV) devices remains poor. Therefore, understanding the degradation mechanisms and identifying potential solutions to improve device stability is critical to enabling the widespread commercialization of OPVs. Herein, simple filtration of the PBDB-T:ITIC photoactive layer (PAL) solution prior to film deposition is demonstrated to enhance OPV device operational stability without compromising initial device performance. The effect of filtration, a commonly used but poorly understood OPV fabrication step, is investigated using a range of chemical, structural, and optoelectronic methods, on solutions and films. Filtration is found to remove large aggregates from solution without disrupting nanoscale preaggregation, resulting in enhanced acceptor ordering in PBDB-T:ITIC thin films, significantly improving morphological stability and photostability. This simple and facile method is confirmed to be a general strategy that also works for other PBDB-T-containing OPV blends, including Y6-based systems, and highlights how subtle changes in morphology can result in dramatic differences in operational stability. Organic photovoltaic (OPV) stability still hinders commercialization. Here, filtration of the photoactive-layer solution is demonstrated as a general and simple strategy to improve OPV operational stability. Detailed chemical, structural, and optoelectronic investigations of filtration, a commonly used but poorly understood OPV fabrication step, highlight improved acceptor crystallinity as the key, resulting in improved morphological and photostability of the photoactive layer. image