π-Conjugated Carbon-Based Materials for Infrared Thermal Imaging

Infrared (IR) thermal imaging is receiving a great deal of attention due to its wide range of applications. Given multiple issues (like cost and availability) with the inorganic materials currently exploited for IR imaging, there is nowadays a great push of developing organic imaging materials. Carbon-based materials are known to have significant transparency in the visible and IR regions and some are used as transparent conductors. Here, whether pi-conjugated carbon-based materials are suitable for long-wave (LW) and mid-wave (MW) IR imaging applications is computationally assessed. Using density functional theory calculations, the IR-vibrational properties of molecules from acenes to coronenes and fullerenes, and of periodic systems like graphene and carbon nanotubes are characterized. Fullerenes, graphenes, and double-walled carbon nanotubes are found to be very attractive as they are transparent in both the LWIR and MWIR regions, a feature resulting from the absence of hydrogen atoms. Also, it is found that replacing hydrogen atoms in a molecule with deuterium or sulfur atoms can be an efficient way to improve their LWIR or MWIR transparency, respectively. For fused-ring systems having hydrogen atoms on the periphery, designing molecules with trio CH-units is another way to enhance the transparency in the LWIR region.

Automated summary

Infrared (IR) thermal imaging is gaining attention for its wide range of applications. Due to the limitations of inorganic materials used for IR imaging, there is a push towards developing organic imaging materials. This study computationally assessed the suitability of pi-conjugated carbon-based materials for long-wave (LW) and mid-wave (MW) IR imaging applications. The results show that fullerenes, graphenes, and double-walled carbon nanotubes are transparent in both LWIR and MWIR regions.