Performance improvement in three-dimensional heterojunction solar cells by embedding CdS nanorod arrays in CdTe absorbing layers

•CdS nanorod arrays are embedded in CdTe absorbers by facile solution process.•The superior optical absorption of 3D photoelectrode helps to improve the efficiency.•The 3D CdS NR/CdTe photoelectrode possesses larger heterojunction area.•The charge carrier collection of the 3D CdS NR/CdTe photoelectrode is improved.•An enhanced efficiency of the novel heterojunction solar cell is obtained.

Oriented and high-density CdS nanorod arrays are successfully embedded in CdTe absorbing layers by facile and low-cost hydrothermal method and electrodeposition method. The structural, optical and electrical properties of these samples are examined, and the results demonstrate that the high quality three-dimensional heterostructure is obtained. Further investigations reveal that the three-dimensional heterostructure possesses superior optical absorption property to improve the photoelectric conversion efficiency due to the optical scattering from the nanorod array. In addition, photovoltaic property measurements demonstrate that the energy conversion efficiency of the novel three-dimensional heterojunction solar cell is increased by 18.5% in comparison to the standard planar heterojunction solar cell. The observed improvement is mostly attributed to the three-dimensional heterostructure enabling enhanced optical absorption ability, increased heterojunction area and improved charge carrier collection. This study demonstrates that the three-dimensional heterostructure has a potential application in thin film solar cells, and the solution process represents a promising technique for large-scale fabrication of these novel solar cells.

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