Excellent Long-Term Stability of Power Conversion Efficiency in NonFullerene-Based Polymer Solar Cells Bearing Tricyanovinylene-Functionalized n-Type Small Molecules

Abstract

New small molecules having modified acceptor strength and pi-conjugation length and containing dicyanovinylene (DCV) and tricyanovinylene (TCV) as a strongly electron-accepting unit with indacenodithiophene, IDT(DCV)(2), IDT(TCV)(2), and IDTT(TCV)(2), were synthesized and studied in terms of their applicability to polymer solar cells with PTB7-Th as an electron-donating polymer. Intriguingly, the blended films containing IDT(TCV)(2) and IDTT(TCV)(2) exhibited superior shelf life stabilities of more than 1000 h without any reduction in the initial power conversion efficiency. The low-lying lowest unoccupied molecular orbital energy levels and robust internal morphologies of small TCV-containing molecules could afford excellent shelf life stability.