Structural Stability‐Driven Dynamic Range Analysis of Carbon Nanotube Photo‐Thermoelectric Sensors

The optical nature of ultra‐broadband millimeter‐wave–visible‐light non‐destructive inspection requires noise suppression of sensors and their appropriate operations for higher‐intensity laser irradiation to flexibly choose photo‐sources. While carbon nanotube (CNT) soft photo‐thermoelectric sensors facilitate compact ultra‐broadband monitoring, their conventional designs focus on noise. In short, efforts are insufficient for evaluating photo‐response dynamic ranges and the fundamental behavior for higher‐intensity irradiation. This work clarifies the surface adhesiveness of substrates dominantly controls response dynamic ranges of CNT sensors against higher‐intensity photo‐irradiation. The proposed CNT sensor design strategy experimentally demonstrates that higher‐intensity irradiation transfers the inherent pn‐junction photo‐detection interface to undesired n‐type channels. This work suggests adhesive chemicals of the device substrate surface function as unnecessary electron‐donating groups on the entire pn‐junction CNT film triggered by irradiation‐induced heating. The device properly maintains the photo‐detection interface for higher‐intensity irradiation by appropriately designing the material composition and size for CNTs on non‐adhesive substrates. This work realizes the associated CNT sensor operation at 10–100 mV response ranges customizable within diverse instruments. The optimized CNT sensor on non‐adhesive substrates finally expands its photo‐response upper‐limit (112 mV) from that (9.98 mV) on adhesive tapes. Such approaches develop user‐friendly CNT film photo‐thermoelectric sensors and ubiquitous social non‐destructive inspection.