Low-power organic transistors: For internet-of-things applications, transistors that deliver high signal amplification (high gain) at low power will help conserve power and extend battery life. Jiang et al. used inkjet printing to fabricate an organic transistor in which silver metal contacts form a low Schottky barrier (less than 0.2 electron volt) with an organic semiconductor. The transistor delivered gain near the theoretical limit at a power below 1 nanowatt and detected electrophysiological signals from the skin with a wearable device. Science , this issue p. 719

Almost-off transistors: Wearable devices and environmental sensors ideally should consume very little power to avoid the need for batteries that would have to be replaced. Lee and Nathan developed a thin-film transistor (TFT) from In-Ga-Zn-O thin films. To make the material less conductive, the films were fabricated to avoid oxygen vacancies. The TFT operated at ultralow power (less than 1 nW) and at switching voltages of less than 1 V with very high intrinsic gain. The devices work by changing the height of the so-called Schottky barrier formed between the semiconductor gate material and the metal drain contact. Science , this issue p. 302

Cu₂O nanoparticles with controllable facets are of great significance for photocatalysis. In this work, the surface termination and facet orientation of Cu₂O nanoparticles are accurately tuned by adjusting the amount of hydroxylamine hydrochloride and surfactant. It is found that Cu₂O nanoparticles with Cu-terminated (110) or (111) surfaces show high photocatalytic activity, while other exposed facets show poor reactivity. Density functional theory simulations confirm that sodium dodecyl sulfate surfactant can lower the surface free energy of Cu-terminated surfaces, increase the density of exposed Cu atoms at the surfaces and thus benefit the photocatalytic activity. It also shows that the poor reactivity of the Cu-terminated Cu₂O (100) surface is due to the high energy barrier of holes at the surface region.