Activating π‐Electron Conjugated Networks of Self‐Assembled Multilayers for 21.1% Efficiency Organic Solar Cells

Abstract

ABSTRACT Self‐assembled monolayers suffer from the insufficient electrical conductivity, stemming from their ultrathin nature and disordered molecular orientation. Here we report a π‐skeleton unit of 3,6‐dibenzothiophen‐9 H ‐carbazol to building a self‐assembled multilayer (SAMUL) that exhibits superior carrier transport and outstanding resistance to external stimuli. The π‐expanded skeleton effectively enhanced the molecular crystallinity and face‐on orientation, which successfully activated a large π‐electron conjugated network within SAMULs. This conjugated network structure greatly broadens the delocalization region of free radicals, which not only significantly enhances the electrical conductance and hole‐transporting capability, but also reinforces the photochemical stability. Consequently, a record‐high efficiency of 21.13% (certified as 20.77%) with a notable fill factor of 83.48% was achieved for binary organic solar cells. This work provides a new inspiration for the molecular skeleton design in organic electronics.