Photovoltaic Blend Microstructure for High Efficiency Post-Fullerene Solar Cells. To Tilt or Not To Tilt?

• DOI: 10.1021/jacs.9b03770
• Publication Date: 2019-08-05T12:14:41Z
• Authors: Gang Wang; Steven M. Swick; Micaela Matta; Subhrangsu Mukherjee; Joseph W. Strzalka; Jenna Leigh Logsdon; Simone Fabiano; Wei Huang; Thomas J. Aldrich; Tony Yang; Amod Timalsina; Natalia Powers-Riggs; Joaquin M. Alzola; Ryan M. Young; Dean M. DeLongchamp; Michael R. Wasiel...; Kevin L. Kohlstedt; George C. Schatz; Ferdinand S. Melk...; Antonio Facchetti; Tobin J. Marks
• Keywords: 01 natural sciences; 7. Clean energy; 0104 chemical sciences

Achieving efficient polymer solar cells (PSCs) requires a structurally optimal donor–acceptor heterojunction morphology. Here we report the combined experimental and theoretical characterization of benzodithiophene–benzothiadiazole donor series (PBTZF4-R; R = alkyl substituent) blended with non-fullerene acceptor ITIC-Th analyze effects substituent dimensions on blend morphology, charge transport, carrier dynamics, PSC metrics. Varying has pronounced effect morphology direct link between domain purity, to some extent dimensions, generation collection. The smallest yields highest power conversion efficiency (PCE, 11%), reflecting relatively small, high-purity domains possibly benefiting from "matched" polymer–small molecule orientations. distinctive morphologies arising substituents are investigated using molecular dynamics (MD) simulations which reveal that dictate well-defined set conformations, in turn driving chain aggregation and, ultimately, various film mixing small molecules. A straightforward energetic parameter explains morphological trends, hence PCE, suggests strategies for selection optimize materials morphologies.