Organic Solar Cells: Electrostatic Stabilization of Organic Semiconductor Nanoparticle Dispersions by Electrical Doping

• Published in: Advanced functional materials Vol. 32; no. 33
• Main Authors: Manger, Felix, Marlow, Philipp, Fischer, Karen, Nöller, Manuel, Sprau, Christian, Colsmann, Alexander
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.08.2022
• Subjects: Copolymers; Dispersions; Doping; electrical doping; electrostatic stabilization; Materials science; Nanoparticles; nanoprecipitation; organic nanoparticles; organic solar cells; Photovoltaic cells; Polymer blends; Solar cells; Surfactants; Tetracyanoquinodimethane
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202202566

Organic semiconductor nanoparticle dispersions are electrostatically stabilized with the p‐doping agent 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ), omitting the need for surfactants. Smallest amounts of F4TCNQ stabilize poly(3‐hexylthiophene) dispersions and reduce the size of the nanoparticles significantly. The concept is then readily transferred to synthesize dispersions from a choice of light‐harvesting benzodithiophene‐based copolymers. Dispersions from the corresponding polymer:fullerene blends are used to fabricate organic solar cells (OSCs). In contrast to the widely used stabilizing surfactants, small amounts of F4TCNQ show no detrimental effect on the device performance. This concept paves the way for the eco‐friendly fabrication of OSCs from nanoparticle dispersions of high‐efficiency light‐harvesting semiconductors by eliminating environmentally hazardous solvents from the deposition process. A novel method to stabilize organic semiconductor nanoparticle dispersions is reported. The nanoparticles are charged by electrical doping with a strong molecular acceptor. This electrostatic stabilization allows the synthesis of concentrated nanoparticle dispersions in the absence of surfactants and the eventual fabrication of organic solar cells thereof. The method is readily applicable to a choice of semiconducting and light‐harvesting polymers.