Assembly of CdS quantum dots onto mesoscopic TiO2 films for quantum dot-sensitized solar cell applications
Assembly of CdS quantum dots onto mesoscopic TiO2 films for quantum dot-sensitized solar cell applications
复制标题
DOI：
10.1088/0957-4484/19/04/045602
复制
发表时间：
2008-01
期刊：
影响因子：
3.5
通讯作者：
Yu-Jen Shen;Yuh‐Lang Lee
中科院分区：
文献类型：
--
作者：
Yu-Jen Shen;Yuh‐Lang Lee
采用巯基琥珀酸（MSA）对胶体硫化镉（CdS）量子点（QDs）进行表面修饰，得到了具有羧酸基（MSA - CdS）的表面。然后利用羧基/TiO2相互作用将MSA-CdS量子点组装到裸露的TiO2介孔膜上。用3-巯基丙基三甲氧基硅烷（MPTMS）或3-氨基丙基甲基二氧基硅烷（APMDS）对TiO2薄膜进行表面修饰，分别制备巯基（-SH）或氨基（-NH2）端接表面，与CdS量子点结合。实验结果表明，mptms改性膜对CdS量子点的吸附率和吸附量最高，这是由于巯基/CdS相互作用较强。相比之下，裸TiO2薄膜上量子点的吸附速率和掺入量远低于硅烷改性薄膜。cds敏化TiO2电极的入射光子电流转换效率（IPCE）为：裸TiO2为20% (400 nm)， MPTMS-TiO2为13%，APMDS-TiO2为6%。黑暗条件下的电流-电压测量结果表明，MPTMS和apmds修饰电极上的暗电流较大，表明cd在这些TiO2薄膜上的覆盖率较低。这一结果归因于CdS量子点在介孔瓶颈处的快速吸附速率抑制了量子点深入孔内区域的传输。对于裸露的TiO2薄膜，cd的掺入量越少，能量转换效率越高，表明形成了覆盖较好的CdS量子点单层。羧酸/TiO2相互作用对MSA-CdS量子点的中等吸附率是量子点在介孔TiO2薄膜上有效组装的原因。
Colloidal cadmium sulfide (CdS) quantum dots (QDs) were prepared and surface modified by mercaptosuccinic acid (MSA) to render a surface with carboxylic acid groups (MSA–CdS). The MSA–CdS QDs were then assembled onto bare TiO2 mesoporous films using the carboxylic groups/TiO2 interaction. The TiO2 film was also surface modified by 3-mercaptopropyl trimethoxysilane (MPTMS) or 3-aminopropyl-methyl diethoxysilane (APMDS) to prepare, respectively, a thiol (–SH) or amino (–NH2) terminated surface for binding with the CdS QDs. The experimental results showed that the MPTMS-modified film has the highest adsorption rate and adsorption amount to the CdS QDs, attributable to the strong thiol/CdS interaction. In contrast, the adsorption rate and incorporated amount of the QDs on the bare TiO2 film are much lower than for the silane-modified films. The incident photon-to-current conversion efficiency (IPCE) obtained for the CdS-sensitized TiO2 electrode was about 20% (at 400 nm) for the bare TiO2, 13% for the MPTMS–TiO2, and 6% for APMDS–TiO2. The current–voltage measurement under dark conditions reveals a higher dark current on the MPTMS- and APMDS-modified electrodes, indicating a lower coverage ratio of CdS on these TiO2 films. This result is attributed to the fast adsorption rate of CdS QDs on the bottleneck of a mesopore which inhibits the transport of the QDs deep into the inner region of a pore. For the bare TiO2 film, the lower incorporated amount of CdS but higher energy conversion efficiency indicates the formation of a better-covered CdS QDs monolayer. The moderate adsorption rate of MSA–CdS QDs using the carboxylic acid/TiO2 interaction is responsible for the efficient assembly of QDs onto the mesoporous TiO2 films.