Sustainable and transparent fish gelatin films for flexible electronic devices
Corresponding authors: Yu Haidong, Nanjing University of technology; Liu juqing, Nanjing University of technology; Huang Wei, Nanjing University of technology authors: Xiaopan Zhang, tengyang ye, Xianghao Meng, Zhihui Tian, Lihua Pang, Yaojie Han, Hai Li, Lu Lu Lu, Fei Xu, Hai Dong Yu, juqing Liu, Wei Huang*
ACEL devices have the advantages of simple structure, large area, low power consumption, convenient production and low cost. They are widely used in outdoor landscape lighting, billboards, instruments and special occasions (airports, hospitals, museums) and other dual-use fields. With the rapid development of information display lighting technology and the gradual enhancement of environmental protection awareness of the public, people have higher and higher requirements for the lighting technology. On the one hand, people expect to give the light-emitting devices such as flexible and extensible functions, and expand their applications in the field of flexible and wearable electronic devices (such as electronic skin); on the other hand, they expect the large demand of light-emitting devices to be green and environmental friendly To reduce the harm of e-waste to the environment. Therefore, it is of practical significance to develop ACEL luminescent technology with good flexibility and environmental protection. Generally, the basic requirement of developing flexible light-emitting devices is that the device can still maintain its performance when it is bent, folded, twisted and other deformations. Therefore, it is necessary to use transparent flexible substrate and integrate it with luminescent materials to realize this kind of flexible AC light-emitting device. However, at present, the flexible transparent substrate is mainly plastic materials, which are mostly made of non renewable crude oil, which are difficult to degrade and will seriously pollute the environment. Therefore, an environmentally friendly transparent flexible substrate material is developed to fabricate flexible ACEL devices.
In order to solve these problems, Huang Wei, academician of Advanced Materials Research Institute of Nanjing University of technology, Yu Haidong and Professor Liu juqing developed a flexible ACEL device for preparing transparent film substrate from fish gelatin extracted from fish scale waste. This gelatin film has a light transmittance of 91.1% and a surface roughness of 0.5 nm in the visible light range, which is comparable to the commercialized PET film (Fig. 1). Fish gelatin film can not only be bent and twisted at will, but also be folded into different shapes as required. Moreover, fish gelatin film has good corrosion resistance, and it can still keep its complete shape after soaking in ethanol, methanol, tetrahydrofuran and other organic solvents for 24 hours. It can be seen that fish gelatin film is an ideal substrate material for flexible electronic devices such as alternating current light-emitting devices, field effect transistors and perovskite solar cells.
Figure 1. Appearance, surface roughness and corrosion resistance of fish gelatin film.
Compared with the traditional plastic substrate, fish gelatin film also has the advantages of recyclability, easy degradation and good biocompatibility (Fig. 2). In order to verify the recyclable characteristics of fish gelatin film, the author dissolved the prepared fish gelatin film in warm water, and then poured the obtained fish gelatin solution into a plastic petri dish, after drying and molding, a new fish gelatin film can be obtained. After this circulation for many times, the 800 nm red light transmittance of fish gelatin film can still maintain more than 90%. In addition, the discarded gelatin film can be biodegraded in the soil. The results show that fish gelatin film can be completely degraded within 24 days after being buried in soil.
Figure 2. Recyclability and biodegradability of fish gelatin film.
In order to prepare the transparent electrode of ACEL device, silver nanowires (Ag NWS) were deposited on the surface of fish gelatin film. After 500 times bending, the visible light transmittance of the electrode is as high as 82.3%, and the square resistance is still as low as 22.4 Ω SQ-1, showing excellent bending resistance (Fig. 3). After the thin film electrode is connected in series with the LED bulb, it is found that the LED bulb will continue to emit light when the thin film electrode is bent into different degrees, which shows that the thin film electrode has excellent conductivity, and its application in ACEL devices can ensure stable electrical signal output.
Figure 3. When the transparent film electrode is bent to different degrees, the LED bulb in the circuit still lights continuously.
A spin coating method is used to add a light-emitting layer on the surface of the Ag NWS electrode, and the Ag NWS is used as the top electrode of the device. As can be seen from the SEM cross section (as shown in Fig. 4), the whole device is a typical sandwich structure, and the functional layers are closely connected. Different from the traditional single-sided light-emitting device, the flexible device can emit light from both sides. At 300 V and 400 Hz, the luminous intensity is as high as 56 CD m-2. The device shows good bending resistance, even after 1000 times of continuous bending, the luminous intensity of the device does not decrease significantly. The device was immersed in 80 ℃ hot water and completely dissolved in 3 minutes, indicating that it is an environmental friendly photoelectric product.
Figure 4. ACEL device and performance based on fish gelatin conductive electrode.
In conclusion, transparent flexible substrate with high transmittance is the key to construct high performance ACEL devices. Fish gelatin extracted from fish scale waste can be used to prepare high performance, sustainable and degradable flexible ACEL devices. The preparation method of fish gelatin film is simple and cheap, which is suitable for low cost and large-scale production. The research results show that fish gelatin film has unique advantages as the substrate of flexible AC light-emitting devices, and has a good prospect in the application of other flexible electronic devices.
Original text (scan or long press QR code, and then go to the original page after identification): sustainable and transparent fish gelatin films for flexible electronic devices Xiaopan Zhang, tengyang ye, Xianghao Meng, Zhihui Tian, Lihua Pang, Yaojie Han, Hai Li, gang Lu, Fei Xu, Hai Dong Yu *, juqing Liu *, Wei Huang * ACS Nano, 2020, DOI: 10.1021/acsnano.9b09880Publication Date: March 18, 2020Copyright ? 2020 American Chemical Society
Tutor introduction
Huang Wei https://www.x-mol.com/university/factory/27680 in Haidong https://www.x-mol.com/university/factory/27722 Liu juqing https://www.x-mol.com/university/factory/27718
(from ACS Publications)
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