Phase Transformations of Copper Sulfide Nanocrystals: Towards Highly Efficient Quantum-Dot-Sensitized Solar Cells.
Owing to their high electrical conductivity, tunable plasmonic absorption spectra, low cost, and abundance in nature, Cu2-x S nanocrystals are of great interest as functional materials for photovoltaic and photothermal applications. With the aim of developing low-cost high-efficiency quantum-dot-sensitized solar cells, solution-processed Cu2-x S nanocrystal films are synthesized and their phase transformations upon thermal treatment are investigated. A combination of experimental results and theoretical analysis illustrates the thermodynamic evolution of the crystal structures and the composition caused by the thermal-annealing process. The use of Cu2-x S nanocrystal films as counter electrodes in quantum-dot-sensitized solar cells is also explored. The devices have an optimized power-conversion efficiency of 5.81 % for tetragonal Cu2 S nanocrystal films that are derived from annealed Cu1.8 S nanocrystal films.
School of Physics, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing, 100081, China.
Lige
L
Liu
School of Physics, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing, 100081, China.
Chang
C
Liu
School of Materials Science & Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing, 100081, China.
Wenping
W
Fu
School of Physics, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing, 100081, China. luogen@bit.edu.cn.
Luogen
L
Deng
School of Materials Science & Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing, 100081, China. hzzhong@bit.edu.cn.
Haizheng
H
Zhong
copper sulfide nanocrystals; phase transformations; quantum dots; solar cells; thin films