?A-?-A? type naphthalimide-based cathode interlayers for efficient organic solar cells

In this work, we designed and synthesized two A-It-A structural small molecules based on N-dimethylamino-propyl-1,8-naphthalimide with It-bridge, namely 4,4'-(thiophene-2,5-diyl)bis(2-(3-(dimethylamino)propyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione) (ONTN) and 4,4'-(1,4-phenylene)bis(2-(3-(dimethylamino)propyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione) (ONBN), which are used as cathode interfacial materials (CIMs) to sys-tematically reveal the effect of It-bridge of 1,8-naphthalimide-based cathode interlayers for efficient organic solar cells (OSCs). Compared with ONBN, ONTN shows higher decomposition temperature, more red-shift absorption, lower LUMO and higher HOMO energy levels, higher electron mobility and conductivity, and more uniform film morphology. Both molecules exhibit excellent thermal stability and high light transmittance. The OSCs based on ONTN with PBDB-T:ITIC as active layer demonstrate a power conversion efficiency (PCE) of 10.38%, higher than the control device of ONBN (a PCE of 9.04%). It turns out that thiophene It-bridge 1,8-naphthalimide-based ONTN got better performance as CIMs than that of ONBN with benzene It-bridge.

Automated summary

In this work, two small molecules based on N-dimethylamino-propyl-1,8-naphthalimide with different It-bridges, ONTN and ONBN, were designed and synthesized as cathode interfacial materials (CIMs) for efficient organic solar cells (OSCs). Compared with ONBN, ONTN showed higher thermal stability, red-shift absorption, lower LUMO and higher HOMO energy levels, higher electron mobility and conductivity, and more uniform film morphology. The OSCs based on ONTN achieved a higher power conversion efficiency (PCE) of 10.38% compared to the control device of ONBN (PCE of 9.04%).