Effects of Electron-Donating and Electron-Accepting Substitution on Photovoltaic Performance in Benzothiadiazole-Based A–D–A′–D–A-Type Small-Molecule Acceptor Solar Cells

A–D–A′–D–A-type nonfused-ring acceptors (NFRAs) have recently received extensive attention because of their suitable tuning of absorption spectra, frontier energy levels, and promising sunlight har...