High‐Performance Solution‐Processed Small‐Molecule Solar Cells Based on a Dithienogermole‐Containing Molecular Donor

A novel dithienogermole-containing a small-molecule donor termed p-DTG(FBTTh2)2 is synthesized and characterized, and its optical, thermal, and electrical properties are found to be comparable to its silicon analogue (p-DTS(FBTTh2)2). Solar cells based on an active layer of p-DTG(FBTTh2)2 and the fullerene PC70BM exhibit a power conversion efficiency of up to 6.9%, indicating that p-DTG(FBTTh2)2 is an excellent small-molecule donor.