Highly Transparent and Flexible Nanopaper Transistors

Renewable and clean “green” electronics based on paper substrates is an emerging field with intensifying research and commercial interests, as the technology combines the unique properties of flexibility, cost efficiency, recyclability, and renewability with the lightweight nature of paper. Because of its excellent optical transmittance and low surface roughness, nanopaper can host many types of electronics that are not possible on regular paper. However, there can be tremendous challenges with integrating devices on nanopaper due to its shape stability during processing. Here we demonstrate for the first time that flexible organic field-effect transistors (OFETs) with high transparency can be fabricated on tailored nanopapers. Useful electrical characteristics and an excellent mechanical flexibility were observed. It is believed that the large binding energy between polymer dielectric and cellulose nanopaper, and the effective stress release from the fibrous substrate promote these beneficial properties. Only a 10% decrease in mobility was observed when the nanopaper transistors were bent and folded. The nanopaper transistor also showed excellent optical transmittance up to 83.5%. The device configuration can transform many semiconductor materials for use in flexible green electronics.



Nanopaper with optimal transmittance and surface smoothness was prepared based on nanostructured cellulose fibers. Nanopaper shows much lower surface roughness and much higher transparency than traditional paper. Highly transparent and flexible OFETs were successfully fabricated on the properly designed nanopaper. The nanopaper OFETs exhibit good transistor electrical characteristics. To demonstrate the flexibility of nanopaper OFETs, devices were measured before and during bending. Only a 10.2% and a 9.8% decrease in mobility were observed when the device was bent in the direction parallel to the conduction channel direction and vertical to the conduction channel direction, respectively. These excellent optical, mechanical, and electrical properties suggest the great potential of nanopaper FETs in next-generation of flexible and transparent electronics and in a broad range of other cost-efficient and practical applications.

Reference
Highly Transparent and Flexible Nanopaper Transistors
Jia Huang, Hongli Zhu, Yuchen Chen, Colin Preston, Kathleen Rohrbach, John Cumings, and Liangbing Hu
ACS Nano 2013 7 (3), 2106-2113