biostudies-literatureMeng YNational Natural Science Foundation of China (National Science Foundation of China)9840https://www.ebi.ac.uk/biostudies/studies/S-EPMC12594902biostudies-literatureUnknown16(1)The commercialization of organic solar cells (OSCs) requires thick-film active layers, yet current thick-film-compatible acceptor selection based on zero-field mobility is unreliable due to methodological inconsistencies in experimental protocols, fitting models, and single-carrier device configurations. Existing literature indicates that the zero-field mobility in high-performance thick-film devices shows negligible differences compared to thin-film counterparts, thereby invalidating its significance as a selection criterion. This study introduces a protocol identifying critical length - an intrinsic property distinct from zero-field mobility - as the decisive factor for thick-film OSC performance. Comparative studies reveal that enlarged acceptor domains with high critical length yield iNature communicationsCritical length screening enables 19% efficiency in thick-film organic solar cells.PMC1259490212204272Gu RGuo XCheng BDu XChen FZhang MHao XMeng YSun YWang LYin HShi BZhu JGao KMa HJiang DQiao JLu PYan HSun JfalseCritical length screening enables 19% efficiency in thick-film organic solar cells.The commercialization of organic solar cells (OSCs) requires thick-film active layers, yet current thick-film-compatible acceptor selection based on zero-field mobility is unreliable due to methodological inconsistencies in experimental protocols, fitting models, and single-carrier device configurations. Existing literature indicates that the zero-field mobility in high-performance thick-film devices shows negligible differences compared to thin-film counterparts, thereby invalidating its significance as a selection criterion. This study introduces a protocol identifying critical length - an intrinsic property distinct from zero-field mobility - as the decisive factor for thick-film OSC performance. Comparative studies reveal that enlarged acceptor domains with high critical length yield i2025-01-01T00:00:00Z2025 Nov2026-06-05T13:54:16.348Z2026-05-17T03:12:40.057ZS-EPMC125949024120360610.1038/s41467-025-64808-x