Shen Heping, Li Jianbao, Zhao Lin, Zhang Shanshan, Wang Wenli, Oron Dan, Lin Hong
State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Phys Chem Chem Phys. 2014 Apr 7;16(13):6250-6. doi: 10.1039/c3cp54954b.
An inorganic layer and dye molecules have synergistically suppressed the recombination in a quantum dot sensitized solar cell (QDSSC), by the design of a structure featured TiO2-CdS-ZnS-N3 (N3: RuL2(NCS)2 (L = 2,2'-bipyridyl-4,4'-dicarboxylic acid)) hybrid photoanode. When fabricated into solar cells, a cobalt complex-based electrolyte rather than an iodine-based one was employed to obtain an impressive photostability for the devices. Raman and Photoluminescence (PL) measurements revealed that not only the CdS QDs were passivated by both the inorganic layer of ZnS and dye molecule of N3, but also N3 served as an efficient hole scavenger for the CdS QDs due to a type-II energetic alignment between the two sensitizers. This role of N3 as an intermediary in hole extraction from CdS QDs to the electrolyte was further proven by the significant photovoltaic performance improvement of the CdS sensitized solar cell after ZnS deposition and N3 co-sensitization. The overall efficiency of the solar cell incorporated with TiO2-CdS-ZnS-N3 film exceeded the sum of the single CdS QDs and N3 dye sensitized solar cells. This enhancement is ascribed mainly to the synergistic recombination suppression by the inorganic layer ZnS and N3 co-sensitization, leading to inhibited recombination and increased electron lifetime, as illustrated by the electrochemical impedance spectroscopy (EIS) analysis.
通过设计TiO2-CdS-ZnS-N3（N3：RuL2(NCS)2 （L = 2,2'-联吡啶-4,4'-二羧酸））混合光阳极结构，无机层和染料分子协同抑制了量子点敏化太阳能电池（QDSSC）中的复合。将其制成太阳能电池时，采用基于钴配合物的电解质而非基于碘的电解质，以使器件具有出色的光稳定性。拉曼光谱和光致发光（PL）测量表明，不仅CdS量子点被ZnS无机层和N3染料分子钝化，而且由于两种敏化剂之间的II型能量排列，N3还作为CdS量子点的有效空穴清除剂。ZnS沉积和N3共敏化后CdS敏化太阳能电池的显著光伏性能改善进一步证明了N3在从CdS量子点到电解质的空穴提取中作为中间体的作用。结合TiO2-CdS-ZnS-N3薄膜的太阳能电池的整体效率超过了单个CdS量子点和N3染料敏化太阳能电池的效率之和。这种增强主要归因于无机层ZnS和N3共敏化对复合的协同抑制，导致复合受到抑制且电子寿命增加，电化学阻抗谱（EIS）分析表明了这一点。
