Reversible luminescent humidity chromism was found on PEA2MnBr4 between green emission and pink emission through water adsorption and desorption.

Stretchable gas sensors that accommodate the shape and motion characteristics of human body are indispensable to a wearable or attachable smart sensing system. However, these gas sensors usually have poor response and recovery kinetics when operated at room temperature, and especially suffer from humidity interference and mechanical robustness issues. Here, we demonstrate the first fully stretchable gas sensors which are operated at room temperature with enhanced stability against humidity. We created a crumpled quantum dot (QD) sensing layer on elastomeric substrate with flexible graphene as electrodes. Through the control over the prestrain of the flexible substrate, we achieved a 5.8 times improvement in NO response at room temperature with desirable stretchability even under 1000 stretch/relax cycles mechanism deformation. The uniformly wavy structural configuration of the crumpled QD gas-sensing layer enabled an improvement in the antihumidity interference. The sensor response shows a minor vibration of 15.9% at room temperature from relative humidity of 0 to 86.7% compared to that of the flat-film sensors with vibration of 84.2%. The successful assembly of QD solids into a crumpled gas-sensing layer enabled a body-attachable, mechanically robust, and humidity-resistant gas sensor, opening up a new pathway to room-temperature operable gas sensors which may be implemented in future smart sensing systems such as stretchable electronic nose and multipurpose electronic skin.

Recently, a class of Ising anisotropic antiferromagnetic screw chain compounds ACo 2 V 2 O 8 (A =Ba,Sr) [16,17] attracts a lot of research attention. In these compounds, the easy-axis is along the chain direction (c-axis), and the intrachain exchange coupling J z ≈ 5-7 meV [18,19]. Both compounds order at fairly low temperatures (about 5 K), which implies the interchain exchange coupling J ′ ≪ J [20][21][22]. The magnetic order can be suppressed by a transverse field applied in the ab-plane [16,17]. Interestingly, the critical field values and the quantum critical behaviors are very different for fields applied along the [100] and the [110] direction [19,[23][24][25][26][27][28][29]. In BaCo 2 V 2 O 8 , separated 3D and 1D QCPs were suggested with field along the [110] direction at H 20 T [28]. For the field along the [100] direction, H C ∼ 10 T [24], much lower

HgTe colloidal quantum dots (CQDs) are promising absorber systems for infrared detection due to their widely tunable photoresponse in all infrared regions. Up to now, the best-performing HgTe CQD photodetectors have relied on using aggregated CQDs, limiting the device design, uniformity and performance. Herein, we report a ligand-engineered approach that produces well-separated HgTe CQDs. The present strategy first employs strong-binding alkyl thioalcohol ligands to enable the synthesis of well-dispersed HgTe cores, followed by a second growth process and a final postligand modification step enhancing their colloidal stability. We demonstrate highly monodisperse HgTe CQDs in a wide size range, from 4.2 to 15.0 nm with sharp excitonic absorption fully covering short- and midwave infrared regions, together with a record electron mobility of up to 18.4 cm2 V–1 s–1. The photodetectors show a room-temperature detectivity of 3.9 × 1011 jones at a 1.7 μm cutoff absorption edge.