Key Laboratory for Advanced Materials, Institute of Applied Chemistry, East China University of Science and Technology , Shanghai 200237, China.
J Am Chem Soc. 2013 Oct 23;135(42):15913-22. doi: 10.1021/ja4079804. Epub 2013 Oct 10.
Searching suitable panchromatic QD sensitizers for expanding the light-harvesting range, accelerating charge separation, and retarding charge recombination is an effective way to improve power conversion efficiency (PCE) of quantum-dot-sensitized solar cells (QDSCs). One possible way to obtain a wide absorption range is to use the exciplex state of a type-II core/shell-structured QDs. In addition, this system could also provide a fast charge separation and low charge-recombination rate. Herein, we report on using a CdTe/CdSe type-II core/shell QD sensitizer with an absorption range extending into the infrared region because of its exciplex state, which is covalently linked to TiO2 mesoporous electrodes by dropping a bifunctional linker molecule mercaptopropionic acid (MPA)-capped QD aqueous solution onto the film electrode. High loading and a uniform distribution of QD sensitizer throughout the film electrode thickness have been confirmed by energy dispersive X-ray (EDX) elemental mapping. The accelerated electron injection and retarded charge-recombination pathway in the built CdTe/CdSe QD cells in comparison with reference CdSe QD-based cells have been confirmed by impedance spectroscopy, fluorescence decay, and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) analysis. With the combination of the high QD loading and intrinsically superior optoelectronic properties of type-II core/shell QD (wide absorption range, fast charge separation, and slow charge recombination), the resulting CdTe/CdSe QD-based regenerative sandwich solar cells exhibit a record PCE of 6.76% (J(sc) = 19.59 mA cm(-2), V(oc) = 0.606 V, and FF = 0.569) with a mask around the active film under a full 1 sun illumination (simulated AM 1.5), which is the highest reported to date for liquid-junction QDSCs.
寻找合适的全色量子点敏化剂以扩展光捕获范围、加速电荷分离并延迟电荷复合是提高量子点敏化太阳能电池（QDSC）的功率转换效率（PCE）的有效方法。获得宽吸收范围的一种可能方法是使用 II 型核/壳结构量子点的激基复合物态。此外，该系统还可以提供快速的电荷分离和低的电荷复合率。在此，我们报告了使用 CdTe/CdSe II 型核/壳量子点敏化剂，由于其激基复合物态，该敏化剂的吸收范围扩展到红外区域，通过将巯基丙酸（MPA）封端的量子点水溶液滴到膜电极上，将其共价连接到 TiO2 介孔电极。通过能量色散 X 射线（EDX）元素映射证实了整个膜电极厚度内量子点敏化剂的高负载和均匀分布。与参考 CdSe QD 基电池相比，通过阻抗谱、荧光衰减和强度调制光电流/光电压谱（IMPS/IMVS）分析证实了构建的 CdTe/CdSe QD 电池中电子注入的加速和电荷复合途径的延迟。结合高量子点负载和 II 型核/壳 QD 的固有优越光电性能（宽吸收范围、快速电荷分离和缓慢电荷复合），所得 CdTe/CdSe QD 基再生夹层太阳能电池在围绕活性膜的情况下在全 1 太阳光照下（模拟 AM 1.5）表现出创纪录的 6.76%的 PCE（J(sc)=19.59 mA cm(-2)，V(oc)=0.606 V，FF=0.569），这是迄今为止报道的液体结 QDSC 的最高值。
