Preparation And Properties Of Two-dimensional Bi₂Se₃ Flexible Photodetector

With the development of society,photodetectors that convert optical signals into electrical signals have attracted great interest from researchers worldwide owing to its various applications in military and human daily life.Recently,two-dimensional（2D）materials have attracted widespread attention in advanced photodetectors due to its inherent atomically structure with excellent flexibility,superior photoelectric properties and high compatibility with flexible substrates.Topological insulators（TI）are considered as a novel class of 2D materials,topological insulators have aroused researchers’great interests,owing to its unique physical and photoelectric properties,enabling them to widely applicate in new generation of optoelectronic devices.Bismuth selenide（Bi₂Se₃）,which is a typical Z2 topological insulator,has a wide range of applications in the field of photodetectors because of its excellent photoelectric performance,special band gap width and high carrier mobility characteristics.However,the manufacturing process of most existing photodetectors is complicated,time-consuming and expensive,importantly,the most of photodetectors are rigid.In this case,employing a facile and low cost way for constructing high performance flexible photodetector is one of effective strategies to facilitate its practical applications.In this paper,a typical two-dimensional Tl（Bi₂Se₃）nanomaterial is discussed,we explored the photoelectric performance of the photodetector based on Bi₂Se₃ nanosheets,and the flexible performance of the device as well as the optimization of the preparation process.Related work is as follows:1. Bi₂Se₃ nanosheets were obtained via a grinding assisted liquid exfoliation process.A series of characterization methods were used to characterize the micro-morphology and structure of the as-prepared samples.At the same time,photoelectric performance of Bi₂Se₃ nanosheets was test by PEC test system.The results showed that the Bi₂Se₃ nanosheets presented good photoresponse performance and stability under the illumination.In addition,the device can achieve the performance of bending and folding by using a flexible ITO substrate.2. Considering the special advantages of two-dimensional materials in the application of flexible devices,we use Bi₂Se₃ nanosheets as the photosensitive material of flexible photodetectors.As the same time,the photodetector with graphite/Bi₂Se₃/graphite structure is designed and prepared,the flexible device is constructed by using ordinary paper as a flexible substrate,pencil drawing electrodes on paper,and writing functional materials with a Chinese brush.Photoelectric performance of devices was test by Keithley Semiconductor Test System.The results show that the flexible device achieves adjustable photoelectric performance from visible to infrared light,and the as-prepared flexible photodetector mainly responds in the infrared region.At a low bias voltage of 5 V,the photocurrent of the Bi₂Se₃ photodetector is as high as 0.82μA,and the responsivity reaches 26.69μAW^-1.Cyclic bending stability of flexible devices based on pencil drawing graphite electrodes on paper were tested.Under the irradiation of 1064 nm infrared light,the results show that the Bi₂Se₃ flexible photodetector did not show obvious photocurrent attenuation after 1000 bending cycles,and device still maintains excellent switching performance after multiple bending cycles.In addition,the flexible device still maintained 60%of the original photocurrent level under a 160°bending angle.These results demonstrating that the prototype device has excellent electrical stability and long-term flexibility.