Solubility of P3HT in chloroform and chloroform:acetone mixtures: A spin-echo SANS study

Abstract

P3HT is a semiconducting polymer widely used in solution-processable photovoltaic research. Measuring the solubility of P3HT in organic solvents is usually an arduous and time-consuming process. Here we report the presence or absence of P3HT nanoparticle agglomeration in optically opaque solutions of P3HT, with concentrations ranging from 6.2 to 22.0 mgmL(-1), in pure chloroform and in chloroform:acetone mixtures, using the neutron scattering technique, Spin-Echo Small Angle Neutron Scattering (SESANS). We demonstrate in-situ that the solubility of P3HT decreases from similar to 22.0 mg/mL to < 6.2 mg/mL when the amount of acetone in solution increases from 0 vol% to 60 vol%. This work uses the ability of SESANS to probe P3HT nanoparticle aggregates, with dimensions ranging from similar to 1 to several microns, in P3HT solutions with concentrations above the solubility limit.