Zhu Juan, Han Donggeon, Wu Xiaodong, Ting Jonathan, Du Shixuan, Arias Ana C
Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, California 94720, United States.
Institute of Physics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, P. R. China.
ACS Appl Mater Interfaces. 2020 Jul 15;12(28):31687-31695. doi: 10.1021/acsami.0c07299. Epub 2020 Jun 29.
The availability of transparent conductive thin films that exhibit mechanical flexibility and are adapted to low-cost and large-area fabrication is a major obstacle for high-performance flexible thin-film optoelectronics. Here, by combining printing, thin-film deposition, and wet-etching processes, interconnected transparent metal micromesh (TMM) electrodes are reported. Blade-coating is used to generate self-assembled polymer micromesh networks on flexible substrates. The network structures are subsequently converted into conductive metal networks. As-fabricated TMM films display a surface roughness of around 20 nm with thickness down to 50 nm. A transmittance of 86% and a conductance of 80 Ω sq are achieved at the described optimal blade-coating suspension concentration. The electrodes show mechanical flexibility with no conductivity degradation with the smallest bending radius of 1 mm or at repeated bending over 3000 cycles at a bending radius of 15 mm. We successfully demonstrate organic light-emitting diodes (OLEDs) using TMM electrodes via the blade-coating technique. The printed OLEDs have a low turn-on voltage of 3.4 V and can achieve a luminance of over 4000 cd/m at 6.5 V. At a luminance of 100 cd/m, the OLEDs show a current density of 7.6 mA/cm, an external quantum efficiency (EQE) of 3.6%, and a luminous efficacy of 1.4 lm/W.
具备机械柔韧性且适用于低成本大面积制造的透明导电薄膜的可得性，是高性能柔性薄膜光电子学面临的一个主要障碍。在此，通过结合印刷、薄膜沉积和湿法蚀刻工艺，报道了相互连接的透明金属微网（TMM）电极。刮刀涂布用于在柔性基板上生成自组装聚合物微网网络。随后将网络结构转化为导电金属网络。所制备的TMM薄膜表面粗糙度约为20 nm，厚度低至50 nm。在所描述的最佳刮刀涂布悬浮液浓度下，实现了86%的透过率和80 Ω/sq的电导率。电极表现出机械柔韧性，在最小弯曲半径为1 mm时或在弯曲半径为15 mm下重复弯曲超过3000次循环时，电导率均无下降。我们通过刮刀涂布技术成功展示了使用TMM电极的有机发光二极管（OLED）。印刷的OLED开启电压低至3.4 V，在6.5 V时可实现超过4000 cd/m²的亮度。在100 cd/m²的亮度下，OLED的电流密度为7.6 mA/cm²，外量子效率（EQE）为3.6%，发光效率为1.4 lm/W。
