The development of textile-based wearable devices has been a hot research topic in recent years. However, a fabric-supported optical switch has never been reported. Herein, a pair of interdigital silver electrodes and hydrothermally synthesized Bi2S3 nanowires (NWs) were screen-printed successively onto silk fabric to construct a silk fabric-based flexible optical switch. The device showed irradiation power-dependent light-on currents and was able to respond to blue, green and red light. A fast response/recovery time of less than 2 ms could be achieved. After 120 cycles of distortion or bending, the light-on current remained as high as >85%. Bi2S3 NW films with different patterns could be printed on top of the devices without significantly affecting their performance. It was also demonstrated that the system could be utilized to trigger the rotation of an electrical fan. This work may provide a facile approach for the preparation of a silk fabric-based optical switch for wearable electronics.
The direct growth of semiconductor nanowire (NW) arrays horizontally aligned on a substrate is critically important for the applications of NWs in electronic or optoelectronic devices at the circuit level. The strict requirement of lattice matching between a substrate and a material in the covalent epitaxy of crystals makes the wire arrays be grown on the substrates only with similar lattice parameters. Herein, a van der Waals epitaxy route is developed to realize the in-plane growth of large-scale Bi 2 S 3 NW arrays on mica with a large lattice mismatch. The orthorhombic Bi 2 S 3 NWs grow epitaxially with the axial direction of ⟨ 001 ⟩ Bi 2 S 3 along the six symmetric directions of the mica. Transmission electron microscope measurements show that the epitaxial relationships are [ 001 ] Bi 2 S 3 | | [ 100 ] mica and [ 3 2 ¯ 0 ] Bi 2 S 3 | | [ 010 ] mica along the length and width directions of the wires, respectively. More importantly, photodetectors based on Bi 2 S 3 NWs show a wide photoresponse spectrum range from 500 to 980 nm. A high responsivity (5233 A W −1 ) and a specific detectivity (1.8 × 10 12 Jones) are achieved under 830 nm light irradiation with ultralow intensity (64 nW cm −2 ). In addition, the photodetectors exhibit high stability with at least 48 day storage in ambient atmosphere or with 1000 times bending.
With the increasing demand for detection accuracy and sensitivity, dual-band polarimetric image sensor has attracted considerable attention due to better object recognition by processing signals from diverse wavebands. However, the widespread use of polarimetric sensors is still limited by high noise, narrow photoresponse range, and low linearly dichroic ratio. Recently, the low-dimensional materials with intrinsic in-plane anisotropy structure exhibit the great potential to realize direct polarized photodetection. Here, strong anisotropy of 1D layered bismuth sulfide (Bi 2 S 3 ) is demonstrated experimentally and theoretically. The Bi 2 S 3 photodetector exhibits excellent device performance, which enables high photoresponsivity (32 A W −1 ), I on / I off ratio (1.08 × 10 4 ), robust linearly dichroic ratio (1.9), and Hooge parameter (2.0 × 10 −5 at 1 Hz) which refer to lower noise than most reported low-dimensional materials-based devices. Impressively, such Bi 2 S 3 nanowire exhibits a good broadband photoresponse, ranging from ultraviolet (360 nm) to short-wave infrared (1064 nm). Direct polarimetric imaging is implemented at the wavelengths of 532 and 808 nm. With these remarkable features, the 1D Bi 2 S 3 nanowires show great potential for direct dual-band polarimetric image sensors without using any external optical polarizer.
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