Dithienobenzodithiophene-Based Small Molecule Organic Solar Cells with over 7% Efficiency via Additive- and Thermal-Annealing-Free Processing

Here we introduce a novel small molecule based on dithienobenzodithiophene and rhodanine, <b>DTBDT-Rho</b>, developed to study the effect of the rhodanine substitutuent on small molecule bulk heterojunction (BHJ) solar cells. <b>DTBDT-Rho</b> possesses distinct crystalline characteristics, sufficient solubility in chlorinated solvents, and broad absorption properties. Therefore, solution-processed BHJ photovoltaic cells made with <b>DTBDT-Rho</b>:PC₇₁BM blends showed an extremely high power conversion efficiency (PCE; 7.10%); notably, this PCE value was obtained without the use of additives or thermal treatments. To our knowledge, the PCE over 7% is a significantly powerful value among rhodanine-based small molecule BHJ solar cells without additives or thermal treatments