Rational Strategies to Stabilize the Morphology of Non-Fullerene Organic Solar Cells
Huawei Hu, Long Ye, Masoud Ghasemi, Nrup Balar, Jeromy James Rech, Samuel J. Stuard , Wei You, Brendon O'Connor, Harald Ade*
Organic photovoltaics (OPVs) are considered one of the most promising cost-effective options for utilizing solar energy. Recently, the OPV field has been revolutionized by the development of novel non-fullerene small molecular acceptors. With efficiencies now reaching 14% in many systems, the device stability and mechanical durability of non-fullerene OPVs have received less attention. Developing devices with both high performance and long-term stability remains challenging, particularly if the material choice is restricted by roll-to-roll and benign solvent processing requirements and desirable mechanical durability. Furthermore, many reports of OPV blends focus primarily on the device performance aspect of the solar cell and ignore the mechanical durability, which is an important consideration for OPV commercialization. Here we report a rational strategy to design nonfullerene OPVs that exhibit excellent thermal stability and storage stability while retaining high ductility with a two-donor polymer, non-halogenated ink. As a result, a highly efficient, stable, and ductile ternary nonfullerene OPV is achieved. The results indicate that synergistic enhancements can be achieved in more than one parameter. Our study indicates that improved stability and performance can be achieved in a synergistic way without significant embrittlement, which will accelerate the future development and application of non-fullerene OPVs.
H. Hu, L. Ye, M. Ghasemi, N. Balar, J. Rech, S. J. Stuard, W. You, B. O'Connor, H. Ade, Adv. Mater. 2019, Under review.