Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
J Am Chem Soc. 2010 Feb 24;132(7):2130-1. doi: 10.1021/ja9098577.
Quantum dots (QDs) are actively explored as alternative sensitizers to inorganic complexes in sensitized solar cells (SSC) due to their interesting physical, optical, and electronic properties. It is thought that the inorganic nature of QDs should provide enhanced stability over the entirely organic or inorganic complex dyes, yet the long-term stability of laboratory QD-SSC devices has not been investigated in detail. A general approach to synthesize high stability QDs involves coating the core material with a wide band gap inorganic shell material (type-I CS QD). However, the electronic structure of the resulting core/shell (CS) structure has potential barriers for both electron and hole transfer, suggesting inefficient charge carrier separation for type-I CS QDs. Herein we demonstrate that type-I CdSe/ZnS CS QDs can effectively sensitize single crystal TiO(2) electrodes and continue to operate in a regenerative mode in an aerated iodide electrolyte for more than 20 h. Core CdSe QDs degrade rapidly in the same electrolyte presumably due to CdI(2) formation. The possibility of exploring new core/shell nanomaterials in a variety of electrolyte/mediator combinations may result in more efficient and stable QD-SSCs.
量子点 (QDs) 由于其有趣的物理、光学和电子特性，正在被积极探索作为敏化太阳能电池 (SSC) 中无机配合物的替代敏化剂。人们认为 QDs 的无机性质应该提供比完全有机或无机配合物染料更高的稳定性，但实验室 QD-SSC 器件的长期稳定性尚未得到详细研究。合成高稳定性 QDs 的一般方法涉及用宽带隙无机壳材料（I 型 CS QD）涂覆核材料。然而，所得核/壳（CS）结构的电子结构对于电子和空穴转移都有势垒，这表明 I 型 CS QDs 的载流子分离效率不高。本文证明 I 型 CdSe/ZnS CS QDs 可以有效地敏化单晶 TiO(2) 电极，并在充气碘化物电解质中以再生模式运行超过 20 小时。在相同的电解质中，核心 CdSe QDs 会迅速降解，这可能是由于形成了 CdI(2)。在各种电解质/介体组合中探索新型核/壳纳米材料的可能性可能会导致更高效和稳定的 QD-SSC。
