Affiliation:
1. Mads Clausen Institute Center for Advanced Photovoltaics and Thin Film Energy Devices (SDU CAPE) University of Southern Denmark 6400 Sønderborg Denmark
2. Brilliant Matters Saint-Augustin-de-Desmaures QC G3A 2C8 Canada
3. Department of Chemistry University of Copenhagen 2100 Copenhagen Ø Denmark
4. Department of Energy Engineering School of Energy and Chemical Engineering Perovtronics Research Center Low Dimensional Carbon Materials Center Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Republic of Korea
Abstract
The introduction of nonfullerene acceptors (NFAs) has pushed the power conversion efficiency and organic photovoltaics (OPV) device stability to new standards. In this aspect, removal of trace impurities from one purification stage to the next is frequently stressed throughout the synthesis of photoactive OPV materials and NFAs to obtain the highest‐purity material. However, detailed studies of the effect of purification on device performance are less reported. Herein, the role of NFA trace impurities on the optoelectronic characteristics and lifetime of resulting OPV devices is studied. The optimization of PBDB‐T:ITIC‐X devices, with various ITIC purity levels (X), has been thoroughly studied via a combination of photophysical, chemical, morphological, electrical, and optical characterization techniques, to shine light on the role of these impurities on device performance and lifetime. The findings suggest that, even in materials with larger concentrations of trace impurities, careful tuning can produce high efficiencies. Interestingly, the less‐pure materials lead to longer device lifetimes along with an enhancement in accumulative power generation by a factor 3, compared to the purest ITIC‐based devices. This demonstrates that selecting a material with the highest purity may not always be the best option for NFA OPV and that any positive effects of NFA purification must be carefully considered in light of both the device efficiency and stability.
Subject
Electrical and Electronic Engineering,Energy Engineering and Power Technology,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials