What is the Solubility of PCBM?

Results show that approximately 9-10 mg can at maximum be dissolved per mL of toluene at room temperature, when stirring the solution for a long time (several days). After that time, the dark red-brown solution is (almost) clear/transparent, meaning that the material has fully dissolved. We can, however, not exclude that some of it is still present as un-dissolved nanoparticles, which are not seen by the eye, nor can be easily filtered out. Sonification may lead to a higher solubility, however, may also lead to more of these nanoparticles.