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We consider singular dislocation and disclination fields within a three-dimensional, possibly non-contractible, connected domain, given in terms of piecewise smooth bulk densities and as concentrations over internal surfaces and curves. We obtain conservation laws for the defect fields which characterize the admissibility of defect configurations in the domain. The conservation laws necessarily include global (non-local) conditions whenever the domain has a boundary consisting of multiple, mutually disjoint, connected components, as is the case with a hollow ball or a hollow torus. We demonstrate the applicability of the global conditions for several defect configurations in a hollow ball. • New conservation laws for singular defect densities over non-contractible domains. • Global conditions for domains which have a boundary consisting of multiple, mutually disjoint, connected components. • Consideration of singular description of dislocations and disclinations. • New restrictions on defect configurations within a hollow ball. [ABSTRACT FROM AUTHOR]

Photo detectors are very important for operation of various opto-electronic devices, like night vision camera, thermal imaging, remote sensing and so on. As the sizes of devices are shrinking day by day, it is important to make photo detectors which are small, robust, stable and have good responsitivity. Also the materials should be made from earth abundant elements and can be deposited using simple deposition techniques. Recently, good photo-detection capabilities in the infrared as well as visible range have been reported in metal dichalcogenides (W S e 2 , M o S e 2 , S n S e 2 , S n S 2 , W S 2 , M o S 2 , P t S e 2 , P d S e 2 etc). S n S e 2 is made of earth abundant elements. In this study, we report IR photo response in S n S e 2 nanostructured thin films grown on soda lime glass (SLG) by thermal evaporation technique. IR (1064 nm) photo response behavior of the film is measured at different bias voltages in 100–400 mV range in steps of 100 mV and laser power density of 30–79 m W / c m 2. The responsitivity of the device shows non-saturation of the traps states in the device. The value of responsitivity was 0.796 ± 0.003 mA/W (standard deviation) at 79 m W / c m 2 laser power density and 400 mV bias voltage and the rise/decay times were 276 ms/332 ms, respectively. It is to be noted that the photo response behavior of film was stable and reproducible even after keeping them in atmospheric conditions for many months. This shows the potential of S n S e 2 as a suitable material for various opto-electronic applications. To the best of our knowledge, the present study shows superior values of responstivity and response/recovery time of S n S e 2 thin film on SLG substrate. • SnSe 2 nanostructured thin film was characterized for its optical, structural and microstructural properties. • The optical absorption coefficient of film was of the order of 104/cm. • Photodetection properties of SnSe 2 nanostructured thin film have been studied for IR (1064 nm) radiation. • The value of responsitivity was 0.796 ± 0.003 mA/W (standard deviation) at 79 mW/cm2 laser power density and 400 mV bias voltage and the rise/decay times were 276 ms/332 ms, respectively. • To the best of our knowledge, the present study shows superior values of sensitivity and response/recovery times. [ABSTRACT FROM AUTHOR]

• SnSe nanostructured thin film was deposited on SLG substrate by one step thermal evaporation technique and photodetection property is studied. • The value of responstivity was 1.40 mA/W for IR radiation at 300 mV bias voltage and 1 mW/cm2 laser power density and swift rise/decay times were 5/28 ms, respectively. • Exact cause of the low responstivity has been quantified with the help of the (PL) and time resolved PL. • Different value of the exponent in power law fitting at different bias voltages showed that the e-hole recombination dominates in controlling the responsitivity. Photodetector application lies in the heart of wearable electronics like artificial visibility, smart watch, etc. Among the recently investigating materials, tin-selenide plays an active role. It has paved its way due to diverse field applicability like thermoelectric, gas sensing, etc. Here, the photodetection properties of SnSe film (in the visible and the IR region) deposited on the cheaper substrate soda-lime glass by one-step thermal evaporation technique are reported. For the IR radiation (1064 nm), the film showed a swift response/recovery time of 5/28 ms at 18 mW/cm2 power density and 300 mV bias voltage. For the visible radiation (532 nm), the device showed 9/34 ms response/recovery times at 32 mW/cm2 and 300 mV bias voltage. The carriers' dynamics are investigated using time-resolved photoluminescence (TRPL). TRPL studies showed no sign of the trap or defect states in the film. The different values of the exponent in the power-law fitting at different bias voltages indicated that the electron-hole recombination might be responsible for the low responstivity of such a device and not the trap states. Thus, the exact process responsible for low responstivity is determined. Through detailed characterization, the study showed the path for improvement in the performance of future photodetector devices. [ABSTRACT FROM AUTHOR]