Self-assembled multilayers of CdSe nanocrystals and carboxylate-handled phenylene-based molecules: optical, electrochemical and photoconductive properties
作者:Barbara Vercelli、Gianni Zotti、Anna Berlin、Mariacecilia Pasini、Marco Natali
DOI:10.1039/c0jm04214e
日期:——
A series of linear phenylene-based molecules, bearing carboxylic acid or carboxylate functionalities at both ends, were reacted with (hexadecylamine/stearate)-capped CdSe nanocrystals (7.5 nm diameter) dispersed in CHCl3 to form multilayers on ITO-glass surfaces via layer-by-layer (LBL) alternation. The new multilayered materials were investigated by UV-Vis spectroscopy, cyclic voltammetry, photoelectrochemistry and photoconductivity. The conjugated linkers, with reversible reduction potentials in the range −1.7 to −2.8 V vs. Ag/Ag+, ease charge transport between dots (LUMO at −1.4 V). Photoconduction is dominated by interdot distance and linker characteristics rather than by LUMO energy levels. The logarithm of photoconductivity and linker length are linearly related, as in conduction of molecular wires, and the tunnelling attenuation factor β value is 2.4 nm−1. Comparison of n-type aromatics and p-type oligothiophenes is discussed.
一系列两端具有羧酸或羧酸盐官能团的线性苯烯基分子与分散在 CHCl3 中的(十六烷基胺/硬脂酸盐)封端硒化镉纳米晶体(直径 7.5 nm)反应,通过逐层(LBL)交替在 ITO 玻璃表面形成多层。研究人员通过紫外可见光谱、循环伏安法、光电化学和光电导等方法对这种新型多层材料进行了研究。与 Ag/Ag+ 相比,共轭连接体的可逆还原电位在-1.7 至 -2.8 V 之间,可促进点之间的电荷传输(LUMO 在-1.4 V)。光导主要受点间距离和连接体特性的影响,而不是 LUMO 能级的影响。光导率的对数与链接器长度呈线性关系,就像分子线的传导一样,隧道衰减系数 β 值为 2.4 nm-1。讨论了 n 型芳烃和 p 型低聚噻吩的比较。