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Bendability optimization of flexible optical nanoelectronics via neutral axis engineering

Sangmin Lee1, Jang-Yeon Kwon2, Daesung Yoon3, Handong Cho1, Jinho You3, Yong Tae Kang3, Dukhyun Choi3* and Woonbong Hwang1*

Author affiliations

1 Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja, Namgu, Pohang, Gyungbuk, 790-784, Republic of Korea

2 School of Integrated Technology, Yonsei University, 162-1, Songdo-dong Yeonsu-gu, Incheon, 406-840, Republic of Korea

3 Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, 446-701, Republic of Korea

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Citation and License

Nanoscale Research Letters 2012, 7:256  doi:10.1186/1556-276X-7-256

Published: 15 May 2012

Abstract

The enhancement of bendability of flexible nanoelectronics is critically important to realize future portable and wearable nanoelectronics for personal and military purposes. Because there is an enormous variety of materials and structures that are used for flexible nanoelectronic devices, a governing design rule for optimizing the bendability of these nanodevices is required. In this article, we suggest a design rule to optimize the bendability of flexible nanoelectronics through neutral axis (NA) engineering. In flexible optical nanoelectronics, transparent electrodes such as indium tin oxide (ITO) are usually the most fragile under an external load because of their brittleness. Therefore, we representatively focus on the bendability of ITO which has been widely used as transparent electrodes, and the NA is controlled by employing a buffer layer on the ITO layer. First, we independently investigate the effect of the thickness and elastic modulus of a buffer layer on the bendability of an ITO film. Then, we develop a design rule for the bendability optimization of flexible optical nanoelectronics. Because NA is determined by considering both the thickness and elastic modulus of a buffer layer, the design rule is conceived to be applicable regardless of the material and thickness that are used for the buffer layer. Finally, our design rule is applied to optimize the bendability of an organic solar cell, which allows the bending radius to reach about 1 mm. Our design rule is thus expected to provide a great strategy to enhance the bending performance of a variety of flexible nanoelectronics.

Keywords:
Flexible optical nanoelectronics; Bendability optimization; Neutral axis engineering; Buffer layer