Structural, electrical, electronic and optical properties of melanin films
Structural, electrical, electronic and optical properties of melanin films
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DOI：
10.1140/epje/i2008-10437-9
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发表时间：
2009-03-01
影响因子：
1.8
通讯作者：
Gunnella, R.
中科院分区：
文献类型：
--
作者：
Abbas, M.;D'Amico, F.;Gunnella, R.
我们目前厚，均匀，而平坦的黑色素膜获得使用喷雾沉积。利用扫描电子显微镜（SEM）和原子力显微镜（AFM）研究了薄膜的形貌。温度依赖性的黑色素薄膜的电阻证明了一个类似的字符和滞后的行为与水分子从黑色素膜解吸的不可逆过程。用X射线光电子能谱（XPS）分析了官能团在大分子一级和二级结构中的作用，结果表明5，6-二羟基吲哚-2-羧酸（DHICA）亚基对分子的贡献约为35%。厚膜（800 nm）和薄膜（80 nm）的光吸收的比较表明，当厚度增加时，光谱发生变化。从在真空光电导（PC）在控制温度下测量，我们认为，黑色素膜表现出一种可能的电荷传输机制，通过离域的π态沿着堆叠的平面二级结构。
We present thick, uniform and rather flat melanin films obtained using spray deposition. The morphology of the films was investigated using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Temperature-dependent electrical resistance of melanin thin films evidenced a semiconductor-like character and a hysteretic behavior linked to an irreversible process of water molecule desorption from the melanin film. X-ray Photoelectron Spectroscopy (XPS) was carried out to analyze the role of the functional groups in the primary and secondary structure of the macromolecule, showing that the contribution of the 5,6-dihydroxyindole-2-carboxylic acid (DHICA) subunit to the molecule is about 35%. Comparison of the optical absorption of the thick (800 nm) and thin (80 nm) films showed a spectral change when the thickness increases. From in vacuum photoconductivity (PC) measured at controlled temperatures, we suggest that the melanin films exhibit a possible charge transport mechanism by means of delocalized pi states along the stacked planar secondary structure.