Chang Su-San, Wu Chun-Guey
Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, Republic of China.
J Phys Chem B. 2005 Oct 6;109(39):18275-82. doi: 10.1021/jp0531210.
A current sensing atomic force microscope (CS-AFM) was used to probe the conducting homogeneity and band structures of fully doped polyaniline (PANI) films prepared from in situ chemical polymerization/deposition of aniline on indium tin oxide in various inorganic acids. The charge transport properties of PANI films depend on the film thickness as well as polymerization medium. Fluctuations in conductivity are observed on all acid-doped PANI films and the conducting homogeneity was dependent on the film thickness: the conductivity of thick film is more uniform. The current-voltage (I-V) characteristics of all thick (>200 nm) films displayed a metal-like behavior and conductivity as high as 40 S/cm was detected in high conducting regions of film thicker than 400 nm. Whereas thin (<120 nm) films revealed insulating, semiconducting, and semimetal conducting, wide distribution in conductivity and interband distances (estimated from the I-V ordI/dV-V curves) was found. The interband distances is 0-1.35, 0-1.0, and 0-0.78 eV for thin PANI film prepared from HCl(aq), HClO(4)(aq), and H2SO4(aq), respectively. PANI film (260 nm) prepared from H2SO4(aq) revealed fiberlike morphology, and compared to PANI films prepared from HCl(aq) and HClO4(aq) with similar thickness, it has higher average nanoscale conductivity but lower bulk conductivity. This result could be direct evidence which supports that the bulk conductivity of PANI depended on the carriers hopping between the conducting domains.
利用电流传感原子力显微镜（CS-AFM）探测通过苯胺在各种无机酸中于氧化铟锡上进行原位化学聚合/沉积制备的全掺杂聚苯胺（PANI）薄膜的导电均匀性和能带结构。PANI薄膜的电荷传输特性取决于薄膜厚度以及聚合介质。在所有酸掺杂的PANI薄膜上均观察到电导率的波动，且导电均匀性取决于薄膜厚度：厚膜的电导率更均匀。所有厚（>200 nm）薄膜的电流-电压（I-V）特性呈现出类似金属的行为，在厚度大于400 nm的薄膜的高导电区域检测到高达40 S/cm的电导率。而薄膜（<120 nm）则显示出绝缘、半导体和半金属导电特性，发现其电导率和带间距离（由I-V或dI/dV-V曲线估算）分布较宽。由HCl(aq)、HClO₄(aq)和H₂SO₄(aq)制备的薄PANI薄膜的带间距离分别为0 - 1.35、0 - 1.0和0 - 0.78 eV。由H₂SO₄(aq)制备的PANI薄膜（260 nm）呈现出纤维状形态，与由HCl(aq)和HClO₄(aq)制备的具有相似厚度的PANI薄膜相比，它具有更高的平均纳米级电导率但更低的体相电导率。这一结果可能是支持PANI体相电导率取决于载流子在导电域之间跳跃的直接证据。
