Department of Chemistry, University at Buffalo, The State University of New York Buffalo, New York 14260-3000, United States.
ACS Appl Mater Interfaces. 2013 Sep 11;5(17):8649-54. doi: 10.1021/am402219e. Epub 2013 Aug 23.
We have synthesized water-dispersible cysteinate(2-)-capped CdSe nanocrystals and attached them to TiO2 using one-step linker-assisted assembly. Room-temperature syntheses yielded CdSe magic-sized clusters (MSCs) exhibiting a narrow and intense first excitonic absorption band centered at 422 nm. Syntheses at 80 °C yielded regular CdSe quantum dots (RQDs) with broader and red-shifted first excitonic absorption bands. Cysteinate(2-)-capped CdSe MSCs and RQDs adsorbed to bare nanocrystalline TiO2 films from aqueous dispersions. CdSe-functionalized TiO2 films were incorporated into working electrodes of quantum dot-sensitized solar cells (QDSSCs). Short-circuit photocurrent action spectra of QDSSCs corresponded closely to absorptance spectra of CdSe-functionalized TiO2 films. Power-conversion efficiencies were (0.43±0.04)% for MSC-functionalized TiO2 and (0.83±0.11)% for RQD-functionalized TiO2. Absorbed photon-to-current efficiencies under white-light illumination were approximately 0.3 for both MSC- and RQD-based QDSSCs, despite the significant differences in the electronic properties of MSCs and RQDs. Cysteinate(2-) is an attractive capping group and ligand, as it engenders water-dispersibility of CdSe nanocrystals with a range of photophysical properties, enables facile all-aqueous linker-assisted attachment of nanocrystals to TiO2, and promotes efficient interfacial charge transfer.
我们合成了水溶性半胱氨酸(2-)-封端的 CdSe 纳米晶，并通过一步链接辅助组装将其附着在 TiO2 上。室温合成得到了具有窄而强的第一激子吸收带的 CdSe 魔术尺寸簇（MSCs），其中心位于 422nm。80°C 下的合成得到了具有较宽且红移的第一激子吸收带的规则 CdSe 量子点（RQDs）。半胱氨酸(2-)-封端的 CdSe MSCs 和 RQDs 从水性分散体中吸附到裸露的纳米晶 TiO2 薄膜上。CdSe 功能化的 TiO2 薄膜被掺入量子点敏化太阳能电池（QDSSC）的工作电极中。QDSSC 的短路光电流作用光谱与 CdSe 功能化 TiO2 薄膜的吸收光谱非常吻合。MSC 功能化 TiO2 的功率转换效率为（0.43±0.04）%，RQD 功能化 TiO2 的功率转换效率为（0.83±0.11）%。在白光照射下，基于 MSC 和 RQD 的 QDSSC 的吸收光子到电流的效率约为 0.3，尽管 MSCs 和 RQDs 的电子性质存在显著差异。半胱氨酸(2-)是一种有吸引力的封端基团和配体，因为它使具有各种光物理性质的 CdSe 纳米晶具有水分散性，能够方便地通过全水链接辅助将纳米晶附着到 TiO2 上，并促进有效的界面电荷转移。
