We attribute

these improvements to electron and load transfer being improved through a reduced number of junctions due to increased CNT length. In addition, we conclude that the lengths of SWCNTs in forests that attain heights of 1,500 μm were close to that of the forest height. These findings indicate the need for taller SWCNT forests in the fabrication of buckypaper for high DAPT electrical conductivity and mechanical strength. Recently, Di et al. reported the ultrastrong and highly conducting CNT film by direct drawing from spinnable CNT array, where the tube length is around 220 μm [34]. Our finding in this study suggest the possibility that the properties of CNT directly drawn from CNT forest can be further enhanced by using longer CNT array. In addition, we expect that using tall SWCNT forests would also raise the conductivity and mechanical strength of SWCNT networks in SWCNT/polymer composite materials. Acknowledgement Support

by the New Energy and Industrial Technology Development Organization (NEDO) is acknowledged. Electronic supplementary material Additional file 1: Photograph and Raman spectra of SWCNT forest with different heights. Figure S1. Photograph of SWCNT forest with different heights with Si substrate. Figure S2. Raman spectra of SWCNT forest with different heights (excitation wavelength 532 nm). (PDF 61 KB) References 1. Hu L, Hecht DS, 3-deazaneplanocin A Gruner G: Percolation in transparent and conducting carbon nanotube networks. Nano Lett 2004, 4:2513–2517.CrossRef 2. Bekyarova E, Itkis ME, Cabrera N, Zhao B, Yu AP, Gao JB, Haddon RC: Electronic properties of single-walled

carbon nanotube networks. J Am Chem Soc 2005, 127:5990–5995.CrossRef 3. Unalan HE, Fanchini G, Kanwal A, Du mafosfamide Pasquier A, Chhowalla M: Design criteria for transparent single-wall carbon nanotube thin-film transistors. Nano Lett 2006, 6:677–682.CrossRef 4. Simien D, Fagan JA, Luo W, Douglas JF, Migler K, Obrzut J: Influence of nanotube length on the optical and conductivity properties of thin single-wall carbon nanotube networks. ACS Nano 2008, 2:1879–1884.CrossRef 5. Li ZR, Kandel HR, Dervishi E, Saini V, Xu Y, Biris AR, Lupu D, Salamo GJ, Biris AS: PRIMA-1MET order Comparative study on different carbon nanotube materials in terms of transparent conductive coatings. Langmuir 2008, 24:2655–2662.CrossRef 6. Gruner G: Carbon nanotube films for transparent and plastic electronics. J Mater Chem 2006, 16:3533–3539.CrossRef 7. Miyata Y, Shiozawa K, Asada Y, Ohno Y, Kitaura R, Mizutani T, Shinohara H: Length-sorted semiconducting carbon nanotubes for high-mobility thin film transistors. Nano Res 2011, 4:963–970.CrossRef 8. Wang X, Jiang Q, Xu W, Cai W, Inoue Y, Zhu Y: Effect of carbon nanotube length on thermal, electrical and mechanical properties of CNT/bismaleimide composites. Carbon 2013, 53:145–152.CrossRef 9.