Colorado State University, USA.
J Am Chem Soc. 2011 Feb 9;133(5):1383-90. doi: 10.1021/ja106254h. Epub 2010 Oct 29.
Stoichiometric copper(I) selenide nanoparticles have been synthesized using the hot injection method. The effects of air exposure on the surface composition, crystal structure, and electronic properties were monitored using X-ray photoelectron spectroscopy, X-ray diffraction, and conductivity measurements. The current-voltage response changes from semiconducting to ohmic, and within a week a 3000-fold increase in conductivity is observed under ambient conditions. The enhanced electronic properties can be explained by the oxidation of Cu(+) and Se(2-) on the nanoparticle surface, ultimately leading to a solid-state conversion of the core from monoclinic Cu(2)Se to cubic Cu(1.8)Se. This behavior is a result of the facile solid-state ionic conductivity of cationic Cu within the crystal and the high susceptibility of the nanoparticle surface to oxidation. This regulated transformation is appealing as one could envision using layers of Cu(2)Se nanoparticles as both semiconducting and conducting domains in optoelectronic devices simply by tuning the electronic properties for each layer through controlled oxidation.
使用热注射法合成了等摩尔比的铜（I）硒化物纳米粒子。通过 X 射线光电子能谱、X 射线衍射和电导率测量监测了暴露在空气中对其表面组成、晶体结构和电子性质的影响。电流-电压响应从半导体变为欧姆，在环境条件下，观察到电导率在一周内增加了 3000 倍。这种增强的电子性质可以通过纳米粒子表面上 Cu(+)和 Se(2-)的氧化来解释，最终导致核心从单斜 Cu(2)Se 到立方 Cu(1.8)Se 的固态转化。这种行为是由于晶体中阳离子 Cu 的固态离子导电性以及纳米粒子表面对氧化的高敏感性。这种调控的转变很有吸引力，因为人们可以设想使用 Cu(2)Se 纳米粒子层作为光电设备中的半导体和导电区域，只需通过控制各层的氧化来调节电子性质。
