본 논문에서 특정 파장대의 빛과 반응하여 두 가지 전기적 상태를 가지는 diarylethene 분자를 이용하여 플렉시블 기판 위에 환원된 그래핀 산화물(reduced graphene oxide; rGO)를 전극으로 하는 분자전자소자를 제작 하고 광스위칭(photoswitching) 특성을 연구하였다. 과거 연구에서 PEDOT:PSS/Au를 전극으로 하는 분자소자의 경우, 금의 낮은 투과율(transmittance)로 인해서 가역적인 광스위칭 현상이 관측되지 않았었다. 하지만, 이번 연구에서는 투과성을 좋은 rGO물질을 전극으로 사용하였고, 분자소자를 UV 혹은 visible light 를 노출시킴으로써 가역적인(reversible) 광스위칭 현상을 구현하였다. 플렉시블 기판에서 다양한 bending radius 와 bending cycle 에서도 광스위칭 특성이 잘 유지된다는 것을 확인하였다.

Abstract: Photoswitching molecular devices with reduced graphene oxide (rGO) top electrodes on flexible substrates are fabricated and characterized. It has been reported previously that diarylethene molecular devices with poly-(3,4-ethylenedioxythiophene) stabilized with poly-(4-styrenesulfonic acid)(denoted as PEDOT:PSS)/Au top electrodes can hold two stable electricla conductance states when the devices are exposed to UV or visible light during device fabrication. However, those devices fail to show the reversible switching phenomenon in response to illumination after device fabrication. By employing conducting and transparent rGO top electrodes, it is demonstrated that the diarylethene molecular devices show a reversible switching phenomenon, i.e., the fabricated devices changed their conductance state in response to the alternating illumination with UV and visible light. Furthermore, the molecular devices with rGO top electrodes also exhibit good longtime stability and reliable electrical characteristics when subjected to various mechanical stress (bending radius down to 5 mm and bending cycle over 104).

Authors: Dongku Kim(서울대), Hyunhak Jeong(서울대), Wang-Taek Hwang(서울대), Yeonsik Jang(서울대), Dmytro Sysoiev(콘사츠대), Elke Scheer(콘사츠대), Thomas Huhn(콘사츠대), Misook Min(서울대), Hyoyoung Lee(성균관대) and Takhee Lee(서울대),*
Advanced Functional Materials, Just Accepted Manuscript

Publication Date (Fri): August 21, 2015
DOI: 10.1002/adfm.201502312