Logic Control of Interface-Induced Charge-Trapping Effect for Ultrasensitive Gas Detection with All-Mirror-Image Symmetry

Controlling the type and concentration of charge carriers is at the heart of modern electronics because of its importance to realize functional devices for potential applications in broad areas ranging from integrated circuits and energy conversion to catalysis and chemical/biological detection. Toward this objective, here a straightforward design of a high-performance stimuli-responsive hybrid optoelectronic device with high-level mirror-image symmetry is presented. The device consists of suspended pristine graphene that is in direct contact with photoactive TiO₂ quantum dots. Through a combination of photoexcitation and gate regulation, two types of photoinduced free electrons trapped at the TiO₂/graphene interface with different behaviors are identified, allowing logical control of both the carrier type and charge trapping/detrapping process. Such control leads to the TiO₂-decorated graphene displaying high chemical environment sensitivity. Upon exposure of the photoexcited hybrid device to different gases, such as O₂ as an electron acceptor and NH₃ or H₂ as an electron donor, all-mirror-image sensing with controllable fast response rate and ultralow detection limit in a single optoelectronic device is established. This approach offers novel interface engineering insights to develop high-performance multifunctional environmental/chemical sensors and other optoelectronic devices.