Light-activated electric bistability for evaporated silver nanoparticles in organic field-effect transistors

Significance 

Recent advances in organic electric bistability show undeniable potential in applications in the field of information technology due to enviable compatibility with flexible substrates and subsidized fabrication costs. However, such electrical bistability necessitates stable charge storage, which indicates the force equilibrium for the trapped charge and the memory window is formed. Luckily, the assistance of photo-irradiation has been seen as an efficient approach to obtain an organic electric bistability performance. Application of electric field has been proposed to effectively restrain the release of trapped charges, therefore affecting the corresponding memory behavior. Alternatively, desired charge storage can be achieved by embedding metal nanoparticles into the dielectric layer of organic field-effect transistors. However, the trapped charges have been reported to escape soon, after where a potential barrier such as silver nanoparticles has not been used.

Researchers led by Professor Yuguang Ma at the State Key Laboratory of Luminescent Materials and Devices in South China University of Technology employed photo-irradiation to the active electric bistability behavior in organic field-effect transistors embedded with evaporated metal nanoparticles. They designed a novel operation mode to exhibit the memory behavior and to explore the origin of the formation of stable charge states. Their work is now published in the research journal, Phys.Chem.Chem.Phys.

The research team begun their experiment by selecting n-doped silicon and thermally grown silicon (IV) oxide as the back-gate and first gate inorganic gates dielectrics. They then embedded the evaporated naked silver nanoparticles in the isolated layer of PTB7-based organic field-effect transistors where their electric bistability behavior was successfully activated by photo-irradiation.

The authors observed that the devices displayed no obvious memory behavior in the dark; while under weak photo-irradiation, an excellent memory window was achieved. The team noted that the designed varying operation modes exhibited the memory behavior and enabled exploration of the origin of the formation of stable charge state. Furthermore, the researchers noted that surplus photo-generated electric field was generated by the immobilized photo-generated electrons. This was seen to confine the trapped charge in the charge storage media after the gate voltage and photo-irradiation were detached.

The study shows that evaporated silver nanoparticles has been introduced in a PTB7-based organic field-effect transistor, where the electric bistability behavior has successfully been activated by photo-irradiation. The results by Professor Yuguang Ma research team have shown that the photo-irradiation created more charges at the interface, and the presence of silver nanoparticles allowed effective charge storage of the majority carriers, which increased the drain current and lowered the gate-operating voltage. This implicates that the memory window can be achieved at very low light density and does not require strong adsorption.

PTB7 – polymer poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl][3- fluoro- 2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]  (a classic hole transporting organic photovoltaic polymer)

Light-activated electric bistability for evaporated silver nanoparticles in organic field-effect transistors. Advances in Engineering

About the author

Dr. Tao Han received his B.S. degree from Chongqing University, M.S. degree from central South University in 2011 and Ph.D degree in State Key Laboratory of Luminescent Materials and Devices from South China University of Technology in 2017, respectively. Tao Han is currently working as a teacher in Xiangnan University, mainly focusing on organic semiconductor device. His research interests include polymer photodetector and organic field-effect transistors.

About the author

Prof. Linlin Liu received her PhD in Jilin University in 2008, and then she spent three years one as a postdoc in Prof. Frank Wuerthner’s group in Wuerzburg University. In the end of 2011 she joined South China University of Technology and become a full professor since 2016. Her research interests include organic functional materials and devices, molecular spectroscopy and metal nanoparticles.

About the author

MingYing Wei received his B.S degree in School of Materials Science and Engineering from South China University of Technology. His research mainly focus on exploring the structure of organic field-effect transistors and its applications. He is prescently working in China Mobile.

About the author

Cong Wang received his B.S. degree of engineering in School of Materials Science and Engineering from Wuhan University of Technology in 2014. His research mainly focus on organic field effect transistor and theoretical calculation of quantum chemistry. He is presently working on his Ph.D in the State Key Laboratory of Luminescent Materials and Devices at South China University of Technology.

About the author

Dr. Xiaoyan Wu received his B. S. degree in College of Chemistry from Jilin University in 2011. His research mainly focused on exploring organic light-emitting materials and devices. He received his Ph.D degree in Yuguang Ma’s lab, State Key Laboratory of Supramolecular Structure and Materials, Jilin University. He is presently working in Chinese Academy of Engineering Physics (CAEP)

About the author

Prof. Zengqi Xie received his PhD in Jilin University in 2007, and then he spent one and a half years as a postdoc in Seoul National University and almost three years as a Humboldt Fellow in Wuerzburg University. In the end of 2011 he joined South China University of Technology as a full professor. His research interests include organic functional materials and devices.

About the author

Prof. Yuguang Ma received his PhD degree of polymer chemistry and physics in Jilin University 1991, and then begin his research career at Jilin University. His research interest is focused on organic luminescent materials, whose invented organic electro-phosphorescence, hybridized local and charge-transfer excited state (HLCT) materials, and electrochemical route for crosslinking organic semiconductor films. He have been supported by Outstanding Young Investigator Fund and Chang-Jiang Scholar, and won the State Natural Science Award (2nd prize) of China.

He is now director of the State Key Laboratory of Luminescent Materials and Devices at South China University of Technology.

Reference

Tao Han, Linlin Liu, Mingying Wei, Cong Wang, Xiaoyan Wu, Zengqi Xie and Yuguang Ma. Light-activated electric bistability for evaporated silver nanoparticles in organic field-effect transistors. Phys.Chem.Chem.Phys., 2017, volume 19, page 17653.

 

Go To Physical Chemistry Chemical Physics

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