Overcoming efficiency and stability limits in water-processing nanoparticular organic photovoltaics by
C. Xie, T. Heumüller, W. Gruber, X. Tang, A. Classen, Isabel Schuldes, Matthew Bidwell, Andreas Späth, Rainer H. Fink, Tobias Unruh, Iain McCulloch, Ning Li, Christoph J. Brabec
Nature Communications 9, Article number: 5335, (2018)
water-processing nanoparticular organic photovoltaics
There is a strong market driven need for processing organic photovoltaics from eco-friendly solvents. Water-dispersed organic semiconducting nanoparticles (NPs) satisfy these premises convincingly. However, the necessity of surfactants, which are inevitable for stabilizing NPs, is a major obstacle towards realizing competitive power conversion efficiencies for water-processed devices. Here, we report on a concept for minimizing the adverse impact of surfactants on solar cell performance. A poloxamer facilitates the purification of organic semiconducting NPs through stripping excess surfactants from aqueous dispersion. The use of surfactant-stripped NPs based on poly(3-hexylthiophene) / non-fullerene acceptor leads to a device efficiency and stability comparable to the one from devices processed by halogenated solvents. A record efficiency of 7.5% is achieved for NP devices based on a low-band gap polymer system. This elegant approach opens an avenue that future organic photovoltaics processing may be indeed based on non-toxic water-based nanoparticle inks.
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