Niyonkuru Dieudonné, Camus Anthony, Reali Manuel, Gao Zhaojing, Shadrack Daniel M, Butyaev Oleg, Surtchev Marko, Santato Clara
Department of Engineering Physics, Polytechnique Montréal C.P. 6079, Succ. Centre-Ville Montréal QC H3C3A7 Canada
Department of Chemistry, St. John's University of Tanzania P.O. Box 47 Dodoma Tanzania.
Nanoscale Adv. 2023 Sep 1;5(19):5295-5300. doi: 10.1039/d3na00355h. eCollection 2023 Sep 26.
Eumelanin, the brown-black member of the melanin biopigment family, is a prototype material for sustainable (green) organic electronics. Sepia eumelanin (Sepia) is a type of biosourced eumelanin extracted from the ink sac of cuttlefish. Electron microscopy and scanning probe microscopy images of Sepia show distinguishable near spherical granules with diameters of about 150-200 nm. We have recently reported on predominant electronic transport in printed films of Sepia formulated inks including the (insulating) binder Polyvinyl-butyral (PVB). In that work, we proposed that inter-granular percolative transport, observed for micrometric interelectrode distances, is promoted by the confining action of the PVB binder on the Sepia granules. Considering that inter-granular transport implies intra-granular transport, in this work we proceeded to a nanoscale study of Sepia granules by High Resolution Atomic Force Microscopy (HR-AFM) and Conductive-AFM (c-AFM). We have observed protrusions on the surface of the Sepia granules, suggesting sub-granular structures compatible with the hierarchical development of Sepia, as proposed elsewhere. For films of Sepia formulated inks deposited on gold-coated substrates, c-AFM revealed, for the very first time, a nanoscale electrical response. Nanoscale studies provide the key to structure-property relationships in biosourced materials strategic for sustainable organic electronics.
真黑素是黑色素生物色素家族中的棕黑色成员，是可持续（绿色）有机电子学的原型材料。乌贼墨真黑素（Sepia）是一种从乌贼墨囊中提取的生物源真黑素。Sepia的电子显微镜和扫描探针显微镜图像显示出直径约为150 - 200 nm的可区分的近球形颗粒。我们最近报道了在包含（绝缘）粘合剂聚乙烯醇缩丁醛（PVB）的Sepia配方油墨的印刷薄膜中的主要电子传输。在那项工作中，我们提出，对于微米级的电极间距离观察到的颗粒间渗流传输，是由PVB粘合剂对Sepia颗粒的限制作用所促进的。考虑到颗粒间传输意味着颗粒内传输，在这项工作中，我们通过高分辨率原子力显微镜（HR - AFM）和导电原子力显微镜（c - AFM）对Sepia颗粒进行了纳米级研究。我们观察到Sepia颗粒表面有突起，这表明存在与Sepia的分级结构相兼容的亚颗粒结构，正如在其他地方所提出的那样。对于沉积在镀金基板上的Sepia配方油墨薄膜，c - AFM首次揭示了纳米级的电响应。纳米级研究为可持续有机电子学的生物源材料中的结构 - 性能关系提供了关键。
