Preparation of multilayered CdSe quantum dot sensitizers by electrostatic layer-by-layer assembly and a series of post-treatments toward efficient quantum dot-sensitized mesoporous TiO2 solar cells.
Preparation of multilayered CdSe quantum dot sensitizers by electrostatic layer-by-layer assembly and a series of post-treatments toward efficient quantum dot-sensitized mesoporous TiO2 solar cells.
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DOI：
10.1021/la202892h
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发表时间：
2012-03
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影响因子：
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通讯作者：
Ho Jin;Sukyung Choi;R. Velu;Sungjee Kim;H. Lee
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文献类型：
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作者：
Ho Jin;Sukyung Choi;R. Velu;Sungjee Kim;H. Lee
利用量子点表面的静电相互作用，通过层层组装法在纳米TiO（2）薄膜的介孔表面制备了多层CdSe量子点，并将其作为敏化剂应用于量子点敏化TiO（2）太阳能电池中.为了在一定厚度的TiO（2）膜内最大限度地吸收入射光并产生激子，通过控制溶解量子点溶液中添加的盐浓度并重复LBL沉积几次来优化量子点沉积的实验条件。发现适当的盐浓度对于提供量子点到介孔中的深度渗透是关键的，从而导致在整个TiO（2）基质中的致密且均匀的分布，同时以可控的方式交替地锚定带相反电荷的量子点。一系列的后处理（1）氯化镉（2），（2）热退火，（3）ZnS涂层被认为是非常关键的，在提高整体光伏性能，大概是通过更好的连接量子点，量子点的表面的有效钝化，和高阻抗的复合，这是由透射电子显微镜（TEM）和电化学阻抗谱（EIS）实验证明。在模拟AM 1.5G（100 mW/cm（2））标准光照条件下，采用适当的量子点敏化剂后处理，CdSe量子点敏化TiO（2）太阳能电池的总能量转换效率可达1.9%。
A multilayer of CdSe quantum dots (QDs) was prepared on the mesoporous surface of a nanoparticulate TiO(2) film by a layer-by-layer (LBL) assembly using the electrostatic interaction of the oppositely charged QD surface for application as a sensitizer in QD-sensitized TiO(2) solar cells. To maximize the absorption of incident light and the generation of excitons by CdSe QDs within a fixed thickness of TiO(2) film, the experimental conditions of QD deposition were optimized by controlling the concentration of salt added into the QD-dissolved solutions and repeating the LBL deposition a few times. A proper concentration of salt was found to be critical in providing a deep penetration of QDs into the mesopore, thus leading to a dense and uniform distribution throughout the whole TiO(2) matrix while anchoring the oppositely charged QDs alternately in a controllable way. A series of post-treatments with (1) CdCl(2), (2) thermal annealing, and (3) ZnS-coating was found to be very critical in improving the overall photovoltaic properties, presumably through a better connection between QDs, effective passivation of QD's surface, and a high impedance of recombination, which were proved by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) experiments. With a proper post-treatment of multilayered QDs as a sensitizer, the overall power conversion efficiency in the CdSe QD-sensitized TiO(2) solar cells could reach 1.9% under standard illumination condition of simulated AM 1.5G (100 mW/cm(2)).