Tang Qun, Song Hyun Jae, Byon Hye Ryung, Yang Hyun Jin, Choi Hee Cheul
Department of Chemistry, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784, South Korea.
Langmuir. 2007 Feb 27;23(5):2800-4. doi: 10.1021/la062497h. Epub 2007 Jan 23.
Successful realization of highly crystalline and densely packed Ag2S nanocrystal (NC) films has been achieved by directly converting precursor molecules, Ag(SCOPh), on preheated substrates. When an aliquot of Ag(SCOPh) solution dissolved in trioctylphosphine (TOP) is applied on preheated solid substrates at 160 degrees C, such as SiO2/Si, H-terminated Si, and quartz. Ag2S NC thin films have been formed with instant phase and color changes of the precursor solutions from pale yellow homogeneous solution to black solid films. The average diameter of individual Ag2S NCs forming thin films is ca. 25 nm, as confirmed by examining both isolated Ag2S NCs from thin films and as-made thin film samples by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Powder X-ray diffraction (XRD) pattern shows that the synthesized Ag2S NCs have well-defined monoclinic acanthite phase. Direct precursor conversion process has resulted in densely packed Ag2S NCs with reduced interparticle distances owing to efficient removal of TOP during the reaction. Compared to the devices fabricated by the drop-coating process, Ag2S thin film devices fabricated by direct precursor conversion process have shown a ca. 300-fold increased conductance. Such Ag2S NC devices have also displayed reliable photoresponses upon white light illumination with high photosensitivity (S approximately equal to 1).
通过在预热的衬底上直接转化前驱体分子Ag(SCOPh)，成功实现了高结晶度且紧密堆积的Ag2S纳米晶体（NC）薄膜。当将溶解在三辛基膦（TOP）中的Ag(SCOPh)溶液等分试样涂覆在160℃的预热固体衬底上时，如SiO2/Si、氢终止的Si和石英，Ag2S NC薄膜得以形成，同时前驱体溶液会瞬间发生相和颜色变化，从浅黄色均匀溶液变为黑色固体薄膜。通过分别使用透射电子显微镜（TEM）和扫描电子显微镜（SEM）检查从薄膜中分离出的Ag2S NC和制成的薄膜样品，证实形成薄膜的单个Ag2S NC的平均直径约为25nm。粉末X射线衍射（XRD）图谱表明合成的Ag2S NC具有明确的单斜辉银矿相。直接前驱体转化过程导致Ag2S NC紧密堆积，由于反应过程中TOP的有效去除，颗粒间距离减小。与通过滴涂工艺制造的器件相比，通过直接前驱体转化工艺制造的Ag2S薄膜器件的电导率提高了约300倍。这种Ag2S NC器件在白光照射下也表现出可靠的光响应，具有高灵敏度（S约等于1）。
