Eco-friendly fabrication of organic solar cells: electrostatic stabilization of surfactant-free organic nanoparticle dispersions by illumination

• Published in: Nanoscale Vol. 14; no. 14; pp. 5569 - 5578
• Main Authors: Marlow, Philipp, Manger, Felix, Fischer, Karen, Sprau, Christian, Colsmann, Alexander
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 07.04.2022
• Subjects: Dispersions; Inks; Luminous intensity; Nanoparticles; Optoelectronic devices; Photovoltaic cells; Solar cells; Stability; Surfactants; Thin films
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d2nr00095d

Earlier reports have discussed the manifold opportunities that arise from the use of eco-friendly organic semiconductor dispersions as inks for printed electronics and, in particular, organic photovoltaics. To date, poly(3-hexylthiophene) (P3HT) plays an outstanding role since it has been the only organic semiconductor that formed nanoparticle dispersions with sufficient stability and concentration without the use of surfactants. This work elucidates the underlying mechanisms that lead to the formation of intrinsically stable P3HT dispersions and reveals prevailing electrostatic effects to rule the nanoparticle growth. The electrostatic dispersion stability can be enhanced by photo-generation of additional charges, depending on the light intensity and its wavelength. This facile, additive-free process provides a universal handle to also stabilize surfactant-free dispersions of other semiconducting polymers, which are frequently used to fabricate organic solar cells or other optoelectronic thin-film devices. The more generalized process understanding paves the way towards a universal synthesis route for organic nanoparticle dispersions. Electrostatic effects promote the self-stabilization of surfactant-free P3HT and P3HT : ICBA nanoparticle dispersions in ethanol. Photoexcitation can control the stabilization of P3HT and other organic semiconductor nanoparticle dispersions.