Highly Efficient Copper鈥揑ndium鈥揝elenide Quantum Dot Solar Cells: Suppression of Carrier Recombination by Controlled ZnS Overlayers

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• 作者：Jae-Yup Kim ; Jiwoong Yang ; Jung Ho Yu ; Woonhyuk Baek ; Chul-Ho Lee ; Hae Jung Son ; Taeghwan Hyeon ; Min Jae Ko
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：9
• 期：11
• 页码：11286-11295
• 全文大小：727K
• ISSN：1936-086X

文摘

Copper鈥搃ndium鈥搒elenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO₂ electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date.