Highly responsive hydrazine sensors based on donor–acceptor perylene diimides: impact of electron-donating groups

Abstract

Three high-performance hydrazine sensing devices have been developed based on donor–acceptor perylenediimides (PDIs) with strongly electron-donating piperidinyl (PDI-PY), pyrrolidinyl (PDI-PI) and n-hexylamino (PDI-HE) as substituents at the perylene core. These PDI devices, compared with reported PDI molecules, displayed 1–2 orders of magnitude higher sensitivity, short response/recovery time and a lower detection limit towards hydrazine vapour. Experimental results demonstrated that PDI-HE possessed the most excellent sensing performance due to its larger electron density and well-defined crystalline structure with a smaller π–π distance of 3.55 Å, yet, poor crystalline structure, weak π–π orbital overlap as well as a larger interplanar spacing of 3.62 Å led to the poorest sensing performance of PDI-PY devices. This study clearly reveals that electron-donating substituents can remarkably improve the sensing performance of PDI devices by increasing the density of electrons, meanwhile, the steric hindrance of electron-donating groups can modulate the sensing performance by influencing the crystalline structure, π–π overlap and π–π distance. The excellent sensing performance makes donor–acceptor perylenes one of the candidates with the most potential for fabrication of highly efficient PDI sensing devices.