Subtle Balance Between Length Scale of Phase Separation and Domain Purification in Small-Molecule Bulk-Heterojunction Blends under Solvent Vapor Treatment

A series of solvents with different solubilities for DR3TBDTT and PC71BM, and different boiling points, is used for solvent vapor annealing (SVA) treatment to systematically investigate the solvent-morphologyperformance relationship. The presence of solvent molecules inside bulk-heterojunction (BHJ) thin films promotes the mobility of both donor and acceptor molecules, leading to crystallization and aggregation, which are important in modulating morphology.