Flexible sensors based on two-dimensional layered materials have gained huge attention in the field of intelligent electronics. The cellulose based platform provides a cost-effective way for fabrication of strain or pressure sensing abilities of the sensor. This paper reports a paper based flexible sensor functionalized by 2D-SnSe2 nanosheets for its multifunctional sensing purposes. 2D-SnSe2 nanosheets were synthesized by a high-yield liquid phase exfoliation technique. The multifunctional sensor fabricated using Whatman filter paper was exploited in the pressure range 2 to 100 kPa. The sensor exhibits the excellent stability and reproducibility with high responsivity of 611% and sensitivity of 1.79 kPa–1. The sensor exhibited excellent stability up to 5000 loading cycles. The response time of the pressure sensors is 100 ms, showing optimum sensor structure for future electronics. The sensor shows excellent potential for the online monitoring of a human breath with 3.2–3.5 s/breath. Finally, the paper advocates the great advancement of two-dimensional transition metal dichalcogenides for their applications as high-performance devices.

Herein, we report the significantly enhanced humidity responsiveness of resistive devices based on two-dimensional SnSe2/MWCNT nanohybrids. The multifunctional humidity sensor was exploited to establish a human–machine interface and for human interactive applications such as breath monitoring and sensing of the humidity of human skin for a touchless positioning interface. The sensor exhibited great potential owing to a high surface-to-volume ratio of SnSe2/MWCNT nanohybrids. The sensor has good linear response over a broad humidity range from 10–70% with fast response and recovery. The sensor shows the humidity responsivity of 0.148 in the humidity range of 10–70% and 0.063 for the humidity range of 75–95%. The maximum current sensitivity of 857% is achieved at 95% relative humidity for SnSe2/MWCNT nanohybrids, which is quite higher than the sensitivity obtained for pristine SnSe2 nanosheets. As a high-performance electronic device, the sensor has extremely low noise level and high recognition power for small humidity variations. The present finding advocates the huge development in humidity monitoring for biomedical, intelligent electronics, and industrial applications.

Group II-VI compounds have been investigated largely in last two decades due to their interesting optoelectronic properties. ZnTe, a member of this family, possesses a bandgap around 2.26eV. This material is now a day investigated in thin film form due to its potential towards various viable applications. In this paper, the authors report their investigations on the preparation of ZnTe thin films using vacuum evaporation technique and their structural and optical characterizations. The structural characterization, carried out using an X-ray diffraction (XRD) technique shows that ZnTe used in present case possesses a cubic structure. Using the same data, the micro strain and dislocation density were evaluated and found to be around 1.465×10-3lines-m2and 1.639×1015lines/m2respecctively. The optical characterization carried out in UV-VIS-NIR region reveals the fact that band gap of ZnTe is around 2.2eV in present case. In addition to this, it was observed that the value of bandgap decreases as the thickness of films increases. The direct transitions of the carries are involved in ZnTe. Using the data of UV-VIS-NIR spectroscopy, the transmission coefficient and extinction coefficient were also calculated for ZnTe thin films. Besides, the variation of extinction coefficient with wavelength has also been discussed here.

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According to the performance requirements, either bulk or nanocrystalline form of the material can be used for different types of device applications. In the present study, zirconium triselenide bulk crystals were grown by direct vapour transport technique. The as-grown crystals and powder have been examined under Carl Zeiss optical microscope and scanning electron microscope for morphological studies which revealed the evolution of crystalline phases of the material by the layered kind of growth mechanism. The energy dispersive analysis of X-ray (EDAX) characterization confirms that no impurity is found in the resulting product except the desired material. To study the effect of different wavelength sources (Blue-470 nm, Green-540 nm, Red-670 nm) on bulk zirconium trisulfide photodetectors, pulsed photo response experiment was carried out. The anisotropic behaviour is also revealed using the same sources. Various device parameters like responsivity, sensitivity, detectivity and external quantum efficiency (EQE%) were calculated. The highest responsivity and detectivity of 81.7 µA/W and 3.56 × 1007 Jones were achieved for blue (470 nm) light source respectively.

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