Fine-Tuning the Performance of Ultraflexible Organic Complementary Circuits on a Single Substrate via a Nanoscale Interfacial Photochemical Reaction

Flexible electronics has paved the way toward the development of next-generation wearable and implantable healthcare devices, including multimodal sensors. Integrating flexible circuits with transducers on a single substrate is desirable for processing vital signals. However, the trade-off between low power consumption and high operating speed is a major bottleneck. Organic thin-film transistors (OTFTs) are suitable for developing flexible circuits owing to their intrinsic flexibility and compatibility with the printing process. We used a photoreactive insulating polymer poly((±)endo,exo-bicyclo[2.2.1]hept-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) to modulate the power consumption and operating speed of ultraflexible organic circuits fabricated on a single substrate. The turn-on voltage (Von) of the p- and n-type OTFTs was controlled through a nanoscale interfacial photochemical reaction. The time-of-flight secondary ion mass spectrometry revealed the preferential occurrence of the PNDPE photochemical reaction in the vicinity of the semiconductor–dielectric interface. The power consumption and operating speed of the ultraflexible complementary inverters were tuned by a factor of 6 and 4, respectively. The minimum static power consumption was 30 ± 9 pW at transient and 4 ± 1 pW at standby. Furthermore, within the tuning range of the operating speed and at a supply voltage above 2.5 V, the minimum stage delay time was of the order of hundreds of microseconds. We demonstrated electromyogram measurements to emphasize the advantage of the nanoscale interfacial photochemical reaction. Our study suggests that a nanoscale interfacial photochemical reaction can be employed to develop imperceptible and wearable multimodal sensors with organic signal processing circuits that exhibit low power consumption

Hydrogen Bond-Induced Nitric Oxide Dissociation on Cu(110)

We have studied the dissociation process of nitric oxide (NO) on Cu(110) and the influence of the hydrogen bond with water by means of density functional theory calculations. We have found that an upright NO adsorbed at a short-bridge site and a side-on NO at a hollow site connecting two short-bridge sites are the two most stable molecularly adsorbed states, and the latter is the precursor for the dissociation process. Various NO dissociation pathways under the influences of the hydrogen bonds with water have been investigated. We have found that hydrogen bonds efficiently reduce the activation energy of NO dissociation by the introductions of a water dimer to O and water dimers to both sides of the side-on NO, respectively. More importantly, the promoting effect of water molecules on NO dissociation is dominant only when one of water molecules in a water dimer forms a hydrogen bond with O of the side-on NO. Our results provide a physical insight into the promoting effect of hydrogen bonds with water, which may be helpful in improving the catalytic activity as well as designing novel catalysts for NO reduction