본 연구에서는 물리적 강도가 뛰어나고 고온에서 안정하며 유연한 친환경 소재인 박테리아 셀룰로오스를 기반으로 투명 전도성막을 제조하였다. 전기전도성의 확보를 위해 은나노와이어(AgNW)와 그래핀을 도입하였다. 합성한 AgNW는 평균적으로 길이 약 15 μm, 폭 약 70 nm로 종횡비 214이었다. 종횡비가 클수록 접촉저항을 낮추어 전도성을 개선시키게 된다. 총 7가지의 막을 제조하고 열적 및 전기적 물성을 조사하였다. 또 전도성막으로 제조하기 위해서 BC막을 칼로 길이 2 mm, 깊이 50 μm 간격으로 홈을 파서 직교상의 그물모양을 형성한 후 이 홈에 AgNW와 그래핀을 채워 넣었다. 대표적으로 AgNW 첨가막은 두께 350 μm, 전자농도 1.53×1019/cm3, 전자이동도 6.63×105 cm2/Vs, 비저항 0.28Ω·cm로 가장 우수한 전기적 특성을 지닌 것으로 평가되었다. 또한 그래핀 첨가막은 두께 360 μm, 전자농도 7.74×1017/cm3, 전자 이동도 0.17 cm2/Vs, 비저항 4.78 Ω·cm이었다. 550 nm 광투과는 AgNW 첨가막 98.1%, 그래핀 첨가막 80.9%로 투명한 전도성 막이 형성되었다. 모든 막이 평면과 휜 상태에서 LED 점등 실험에서 전구의 밝기에 차이가 있었으나 불이 켜졌다. 150±5 ℃의 열판에서 박테리아 셀룰로오스 막은 형태가 매우 안정하였으나 같은 두께의 PET는 형태가 심하게 변형되었다. 이러한 연구 결과를 통해 박테리아 셀룰로오스 기반의 투명전도성막을 제조할 수 있는 가능성을 확인하였다.

A transparent film was fabricated based on bacterial cellulose (BC), BC has excellent physical strength and stability at high temperature and it is an environmental friendly flexible material. In order to improve the conductivity, silver nanowire (AgNW) and/or graphene were introduced to the BC membrane. The aspect ratio of the AgNW synthesized in this study was 214, with a length of 15 μm and width of 70 nm. The higher aspect ratio improved the conductivity by reducing the contact resistance. The thermal and electrical properties of 7 types of films prepared were investigated. Each film was fabricated with rectangular shape (2 mm × 2 mm × 50 μm). The films were scored with a net shape by a knife, and filled with AgNW and graphene to bestow conductivity. The film filled with AgNW showed favorable electrical characteristics with a thickness of 350 μm, electron concentration of 1.53×1019, electron mobility of 6.63×105, and resistivity of 0.28. The film filled with graphene had a thickness of 360 μm, electron concentration of 7.74 ×1017, electron mobility of 0.17, and resistivity of 4.78. The transmittances at 550 nm were 98.1% and 80.9%, respectively. All the films were able to light LEDs bulbs although their brightness differed. A thermal stability test of the BC and PET films at 150±5 ℃ showed that the BC film was more stable, whereas the PET film was quickly banded. From these results, it was confirmed that there it is possible to fabricate new transparent conductivity films based on BC.

Graphene Silver Nanowire Bacterial Cellulose Transparent Conductivity Film

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