Browsing by Author "Liu, Yuan"

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A Bilayer 2D-WS2/Organic-Based Heterojunction for High-Performance Photodetectors
(2019-09-01)
Huang, Feng
;
Li, Jing Zhou
;
Xu, Zhu Hua
;
Liu, Yuan
;
Luo, Ri Peng
Two-dimensional (2D) tungsten disulfide (WS2) has inspired great efforts in optoelectronics, such as in solar cells, light-emitting diodes, and photodetectors. However, chemical vapor deposition (CVD) grown 2D WS2 domains with the coexistence of a discontinuous single layer and multilayers are still not suitable for the fabrication of photodetectors on a large scale. An emerging field in the integration of organic materials with 2D materials offers the advantages of molecular diversity and flexibility to provide an exciting aspect on high-performance device applications. Herein, we fabricated a photodetector based on a 2D-WS2/organic semiconductor materials (mixture of the (Poly-(N,N '-bis-4-butylphenyl-N,N '-bisphenyl) benzidine and Phenyl-C61-butyric acid methyl ester (Poly-TPD/PCBM)) heterojunction. The application of Poly-TPD/PCBM organic blend film enhanced light absorption, electrically connected the isolated WS2 domains, and promoted the separation of electron-hole pairs. The generated exciton could sufficiently diffuse to the interface of the WS2 and the organic blend layers for efficient charge separation, where Poly-TPD was favorable for hole carrier transport and PCBM for electron transport to their respective electrodes. We show that the photodetector exhibited high responsivity, detectivity, and an on/off ratio of 0.1 A/W, 1.1 x 10(11) Jones, and 100, respectively. In addition, the photodetector showed a broad spectral response from 500 nm to 750 nm, with a peak external quantum efficiency (EQE) of 8%. Our work offers a facile solution-coating process combined with a CVD technique to prepare an inorganic/organic heterojunction photodetector with high performance on silicon substrate.
High on/off ratio black phosphorus based memristor with ultra-thin phosphorus oxide layer
(2019-11-04)
Wang, Yudan
;
Wu, Facai
;
Liu, Xingqiang
;
Lin, Jun
;
Chen, Jui-Yuan
The scaling down of switching media encounters high leakage current in the traditional oxide material based memristors, resulting in high power consumption of chips. Two-dimensional (2D) materials promise an ultimate device scaling down to atomic layer thickness. Herein, black phosphorus (BP) and its self-assembly phosphorous oxide (BP) memristors are constructed, which leverages the high on/off ratio operation of oxides and low leakage current of 2D materials with high performance. The memristors exhibit reproducible and reliable switching characteristics with the on/off ratio >10(7) and data retention >10(4) s. Depending on the high reproducibility, basic "AND" and "OR" gates have been constructed on flexible substrates. Moreover, on the basis of the symmetry and linearity of conductance in the devices, the neural network simulation for supervised learning presents an online learning accuracy of 91.4%. This work opens an avenue for future flexible electronics.