Photon‐Pen Writing for Metal Oxide‐Based Versatile Nanosensors

Low-temperature processes and simplification of lithographic techniques are key challenges for the fabrication of solution-processed metal oxide-based nanodevices. Recent breakthroughs in location-specific synthetic methodologies involving inkjet printing and photon-activation routes have enabled lithography-free and bottom-up fabrication of such devices. However, a revolutionary strategy to resolve room-temperature direct fabrication of metal oxide-based materials still remains elusive. Here, a pertinent route enabling wafer-scale, location-specific direct-writing, termed "photon-pen writing (PPW)," of functional metal oxide-based devices is proposed. Using PPW, fabrication of elaborate patterns of metal oxides is demonstrated through location-specific dechlorination and subsequent oxidation via thermal energy transfer of a focused infrared laser in ambient environment. By tailoring process parameters, precise manipulation of the chemical and structural features of the PPW-produced metal-oxide patterns are demonstrated. The versatility of the PPW process by realizing a highly sensitive, stable, uniform, and wafer-scale nanosensor array for gas and light detection using PPW-ZnO channel and PPW-ITO electrodes is demonstrated, with 4.1% of response at 50 ppb NO2 and 2.93 +/- 0.23 mu A of photocurrent for 0.76 mW cm(-2), 254 nm UV light. A new route toward wafer-scale production of bespoke nanosensor arrays onto single chip for next-generation nanoelectronics is introduced.