Flexible Visible-Blind Ultraviolet Photodetectors Based on ZnAl-Layered Double Hydroxide Nanosheet Scroll

Abstract

Visible-blind ultraviolet (UV) photodetectors have received a great deal of attention for realizing Internet of Things technologies as well as for monitoring the level of UV exposure to humans. Realizing next-generation flexible and visible-blind UV photodetectors requires development of new functional material systems with easy fabrication, selectively strong UV light absorption, environmental friendliness, and high stability regardless of ambient conditions. Herein, flexible visible-blind UV photodetectors are successfully fabricated on the basis of two-dimensional ZnAl-layered double hydroxide (LDH) nanosheets with scroll structures grown on flexible substrates. The ZnAl-LDH nanosheet scrolls exhibit highly resistive semiconducting properties with a band gap of 3.2 eV and work function of 3.64 eV. The photodetector based on the ZnAl-LDH shows photoresponse in the UV spectral range below 420 nm, indicating visible-blind spectral response. In addition, the UV photodetector shows a maximum responsivity of 17 mA/W under illumination with 365 nm light. Moreover, the flexible photodetector shows reproducible photoresponse even after 1000 bending cycles, which indicates the acceptable stability of the ZnAl-LDH nanosheet scrolls.

Zn–Al Layered Double Hydroxide Film Functionalized by a Luminescent Octahedral Molybdenum Cluster: Ultraviolet–Visible Photoconductivity Response

“…The remarkable point in this study is the determining of the relation between the photoresponse and the temperature or the humidity level which has not been figured out, to the best of our knowledge, in previous reports about LDH-based materials. [28][29][30] Even if a further understanding of this phenomenon should be investigated in the future, we have demonstrated that EPD is an excellent process to easily prepare a Mo6functionalized LDH film exhibiting good mechanical properties. Zn(NO3)2  6H2O (99%) and Al(NO3)3  9H2O ( 98%, pH= 2~4) were purchased from Chameleon reagent.…”

Flexible Titanium Nitride/Germanium-Tin Photodetectors Based on Sub-Bandgap Absorption

“…As shown in Figure d, the detectivity of flat TiN/GeSn PDs at 1550 nm was calculated to be 8 × 10 8 cm Hz –1 W –1 , which is eight times higher than that of flat GeSn PDs. Although the absorption layer of this flexible device is very thin, its detectivity is as good as those of other rigid GeSn PDs. , In addition, it should exhibit a fast photoswitching response time due to the high mobility of single-crystalline GeSn. ,,− These results suggest that the formation of a stable TiN/GeSn Schottky junction is responsible for the observed enhancement in various figure-of-merits of TiN/GeSn PDs.…”

Black Phosphorus Quantum Dots as Hole Capturers in Group-VA Monoelemental Heterostructures for the Application of High-Performance Flexible Photodetectors

“…To evaluate the ability of charge separation and diffusion, the rise time (t r ) and fall time (t f ) of the Bi NSs-BP QD photodetector have been marked in Figure 4c, which are the times between 90 and 10% of the maximum photocurrent density. 45 The t r and t f of the constructed photodetectors are 330 ms and 510 ms at 0 V, respectively. It means that the constructed devices can accomplish photoelectric conversion in a short time.…”

“…In addition, the blue line is the responsivity that could be described according to the following equation: R = I p / PS , where I p , P , and S refer to the photocurrent density, the irradiation intensity, and the effective irradiation area, respectively. , It is clearly demonstrated that when the irradiation intensity is 240 mW/cm 2 , the responsivity achieves a maximum value (∼2.8 μA W –1 ). To evaluate the ability of charge separation and diffusion, the rise time ( t r ) and fall time ( t f ) of the Bi NSs-BP QD photodetector have been marked in Figure c, which are the times between 90 and 10% of the maximum photocurrent density . The t r and t f of the constructed photodetectors are 330 ms and 510 ms at 0 V, respectively.…”