Highly sensitive and stable perylene sensor for ammonia detection: A case study of structure-property relationships

In this contribution, we report three perylenediimides (PDIs) substituted with hydrogen (PDI), mono-nitro (PDIN) and di-nitro groups (PDI2N) at bay positions. The resulting sensing devices, which were composed of self-assembled micro/nanoribbons, exhibited high sensitivity toward ammonia vapor. Among the three PDIs, the PDI2N device displayed the lowest detection limit, as evidenced by its reduction potential of −0.36 eV, and the best ambient stability due to its reduction potential being as low as −4.35 eV. A positive reduction potential and moderate π-π orbital overlap conferred the PDIN device with the highest sensitivity. By contrast, a negative reduction potential of −0.73 eV resulted in a severe lack of carrier density and, therefore, induced the poorest sensitivity in the PDIs device. These results reveal that detection limits are closely associated with the reduction potential of PDIs devices and that ambient stability is determined by the lowest unoccupied molecular orbital energy level. The combined effects of reduction potential and π-π orbital overlap modulated the sensitivity of the PDIs devices. This study not only presents sensitive and ambient-stable PDIs sensing devices but also identifies the critical factors influencing their sensitivity, detection limit, and stability. The excellent sensing performance and extensive theoretical research presented in this work are expected to provide a basis for the design of simple, efficient, and highly stable PDIs sensors.