Department of Chemical Engineering, National Taiwan University of Science and Technology , 43, Section 4, Keelung Road, Taipei 10607, Taiwan, Republic of China.
ACS Appl Mater Interfaces. 2013 Nov 13;5(21):11296-306. doi: 10.1021/am403531q. Epub 2013 Oct 18.
A cadmium-free CuInS2 quantum dot (QD)-sensitized solar cell (QDSC) has been fabricated by taking advantage of the ex situ synthesis approach for fabricating highly crystalline QDs and the in situ successive ionic-layer adsorption and reaction (SILAR) approach for achieving high surface coverage of QDs. The ex situ synthesized CuInS2 QDs can be rendered water soluble through a simple and rapid two-step method under the assistance of ultrasonication. This approach allows a stepwise ligand change from the insertion of a foreign ligand to ligand replacement, which preserves the long-term stability of colloidal solutions for more than 1 month. Furthermore, the resulting QDs can be utilized as sensitizers in QDSCs, and such a QDSC can deliver a power conversion efficiency (PCE) of 0.64%. Using the SILAR process, in situ CuInS2 QDs could be preferentially grown epitaxially on the pre-existing seeds of ex situ synthesized CuInS2 QDs. The results indicated that the CuInS2 QDSC fabricated by the combined ex situ/in situ growth process exhibited a PCE of 1.84% (short-circuit current density = 7.72 mA cm(-2), open-circuit voltage = 570 mV, and fill factor = 41.8%), which is higher than the PCEs of CuInS2 QDSCs fabricated by ex situ and in situ growth processes, respectively. The relative efficiencies of electrons injected by the combined ex situ/in situ growth approach were higher than those of ex situ synthesized CuInS2 QDs deposited on TiO2 films, as determined by emission-decay kinetic measurements. The incident photon-to-current conversion efficiency has been determined, and electrochemical impedance spectroscopy has been carried out to investigate the photovoltaic behavior and charge-transfer resistance of the QDSCs. The results suggest that the combined synergetic effects of in situ and ex situ CuInS2 QD growth facilitate more electron injection from the QD sensitizers into TiO2.
一种不含镉的 CuInS2 量子点 (QD)-敏化太阳能电池 (QDSC) 已通过利用原位合成法制备高结晶度 QD 和原位连续离子层吸附和反应 (SILAR) 法实现 QD 的高表面覆盖的方法来制造。通过超声辅助的简单快速两步法，可以使通过外部分步合成法制备的 CuInS2 QD 变得水溶性。这种方法允许从插入外来配体到配体取代的逐步配体变化，从而保持胶体溶液的长期稳定性超过 1 个月。此外，所得 QD 可用作 QDSC 的敏化剂，并且这种 QDSC 可以提供 0.64%的功率转换效率 (PCE)。使用 SILAR 工艺，可以在预先存在的外部分步合成的 CuInS2 QD 种子上优先外延生长原位 CuInS2 QD。结果表明，通过组合外部分步/原位生长工艺制备的 CuInS2 QDSC 表现出 1.84%的 PCE(短路电流密度=7.72 mA cm(-2)，开路电压=570 mV，填充因子=41.8%)，高于分别由外部分步和原位生长工艺制备的 CuInS2 QDSC 的 PCE。通过发射衰减动力学测量确定的组合外部分步/原位生长方法注入电子的相对效率高于沉积在 TiO2 薄膜上的外部分步合成的 CuInS2 QD。已确定入射光子电流转换效率，并进行了电化学阻抗谱研究以研究 QDSC 的光伏行为和电荷转移电阻。结果表明，原位和外部分步 CuInS2 QD 生长的协同作用有助于从 QD 敏化剂更有效地注入电子进入 TiO2。
