Zhixian Chang

Effect of Crystallization of Cu2ZnSnSxSe4–x Counter Electrode on the Performance for Efficient Dye-Sensitized Solar Cells

Cu2ZnSnSxSe4-x (CZTSSe) counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) are commonly developed with porous structures, but their high surface area could also retard electron transport processes owing to the abundant grain boundaries. Herein, we employed a convenient solution method and a rapid heating process to prepare well crystalline CZTSSe CEs in DSSCs. The influence of crystallization of CZTSSe film on DSSCs performances was discussed in depth. The thermogravimetric analysis, phase morphology, conductivity, and electrochemical characteristics of CZTSSe films were performed. It is found that the rapid heating process is beneficial to the formation of well crystalline film with large grains. As the porosity and grain boundaries in the bulk film are dramatically reduced with the enhanced crystallization, the charge transport process is gradually improved. Using cyclic voltammogram and electrochemical impedance spectroscopy measurements, we propose that the accelerating charge transport is of great importance to the photovoltaic performances of DSSCs due to their superior electrocatalytic activities. As the highest cell efficiency was achieved, well crystalline CZTSSe is an efficient CE catalytic material.

Efficiency enhancement of dye-sensitized solar cells (DSSCs) using ligand exchanged CuInS2 NCs as counter electrode materials

Exploring inorganic ligand capped nanocrystals (NCs) as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs) with high conversion efficiency. Here, we reported the preparation of inorganic ligand capped CuInS2 NCs through a ligand exchange strategy. After ligand exchange, the organic ligand capped on the surface of CuInS2 NCs were exchanged to inorganic ligand S2− without changing the shape, size distribution and crystal structure of CuInS2 NCs. When used as CE materials for dye-sensitized solar cells, the inorganic ligand capped CuInS2 NCs films showed higher electrocatalytic activity and electrical conductivity, thus can significantly improve the efficiency of DSSCs. It should be noted that the conversion efficiency of the DSSC increased by 17 times after the organic ligand capped CuInS2 NCs were exchanged with the inorganic ligand. The study in this work may pave a new pathway to explore highly electrical conductivity materials for DSSCs.

Cu2ZnSnS4–CdS heterostructured nanocrystals for enhanced photocatalytic hydrogen production

The CZTS–CdS heterostructured nanocrystals were designed and synthesized via a wet chemistry approach for the first time. The p–n heterojunction between CZTS core and CdS layer facilitates a effective charge separation and a rapid charge transfer. As expected, these CZTS–CdS-heterostructured nanocrystals show enhanced photocatalytic activities for hydrogen evolution when compared with CZTS and CdS.