Novel CoS sub(2) embedded carbon nanocages by direct sulfurizing metal-organic frameworks for dye-sensitized solar cells

• Published in: Nanoscale Vol. 8; no. 23; pp. 11984 - 11992
• Main Authors: Cui, Xiaodan, Xie, Zhiqiang, Wang, Ying
• Format: Journal Article
• Language: English
• Published: 01.06.2016
• Subjects: Carbon; Durability; Electrical conductivity; Electrical resistivity; Nanostructure; Photovoltaic cells; Platinum; Solar cells
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c6nr03052a

Owing to its excellent electrocatalytic properties, cobalt disulfide (CoS sub(2)) is regarded as a promising counter electrode (CE) material for dye-sensitized solar cells (DSSCs). However, hindered by its relatively poor electrical conductivity and chemical instability, it remains a challenge to apply it into high-performance DSSCs. In this work, we have developed novel CoS sub(2) embedded carbon nanocages as a CE in DSSCs, using ZIF-67 (zeolitic imidazolate framework 67, Co(mim) sub(2), mim = 2-methylimidolate) as a template. The CoS sub(2) samples sulfurized for different time lengths are prepared through a facile solution process. It is found that the sulfurization time can be optimized to maximize the DSSC efficiency and the DSSC based on the CoS sub(2) embedded carbon nanocages sulfurized for 4 hours exhibits the highest photovoltaic conversion efficiency (PCE) of 8.20%, higher than those of DSSCs consisting of other CoS sub(2) CEs and Pt-based DSSC (7.88%). The significantly improved DSSC PCE is contributed by the synergic effect of inner CoS sub(2) nanoparticles and an amorphous carbon matrix, leading to a CE with high catalytic activity, good electrical conductivity and excellent durability. This study demonstrates that the CE based on inexpensive CoS sub(2) embedded carbon nanocages is a prospective substitute to expensive platinum and provides a new approach for commercializing high-efficiency DSSCs.