Abstract
CdTe is an important compound semiconductor for solar cells, and its use in nanowire-based heterostructures may become a critical requirement, owing to the potential scarcity of tellurium. The effects of the CdCl2 heat treatment are investigated on the physical properties of vertically aligned ZnO/CdTe core-shell nanowire arrays grown by combining chemical bath deposition with close space sublimation. It is found that recrystallization phenomena are induced by the CdCl2 heat treatment in the CdTe shell composed of nanograins: its crystallinity is improved while grain growth and texture randomization occur. The presence of a tellurium crystalline phase that may decorate grain boundaries is also revealed. The CdCl2 heat treatment further favors the chlorine doping of the CdTe shell with the formation of chlorine A-centers and can result in the passivation of grain boundaries. The absorption properties of ZnO/CdTe core-shell nanowire arrays are highly efficient, and more than 80% of the incident light can be absorbed in the spectral range of the solar irradiance. The resulting photovoltaic properties of solar cells made from ZnO/CdTe core-shell nanowire arrays covered with CuSCN/Au back-side contact are also improved after the CdCl2 heat treatment. However, recombination and trap phenomena are expected to operate, and the collection of the holes that are mainly photo-generated in the CdTe shell from the CuSCN/Au back-side contact is presumably identified as the main critical point in these solar cells.
Highlights
Increasing interest has been devoted to core-shell semiconductor nanowires (NWs) over the past years due to their potential use in energy-harvesting devices such as nanostructured solar cells [1,2]
The effects of the CdCl2 heat treatment are investigated on the structural ordering, doping, and photovoltaic properties of ZnO/CdTe core-shell NW arrays grown by low-cost deposition techniques
It is found by field-emission scanning electron microscopy (FESEM) images and X-ray diffraction (XRD) measurements that recrystallization phenomena are induced in CdTe NGs by the CdCl2 heat treatment
Summary
Increasing interest has been devoted to core-shell semiconductor nanowires (NWs) over the past years due to their potential use in energy-harvesting devices such as nanostructured solar cells [1,2]. Owing to its wide bandgap energy of 3.3 eV at room temperature, high exciton binding energy of 60 meV, charge carrier separation as well as an alternative absorption channel via the type-II optical transition [13,15], which may significantly improve the light absorption and efficiency of nanostructured solar cells. An alternative route is to deposit CdTe nanoparticles (NPs) on ZnO NWs by immersion or dip coating [24,26,29,32] In both routes, a uniform deposition of the CdTe shell has been reported from the bottom to the top of ZnO NWs. Still, the photovoltaic properties of the resulting nanostructured solar cells are fairly poor [22,24,25,27,29,32]. It is the aim of this paper to reveal the chemical and physical mechanisms following the CdCl2 heat treatment in ZnO/CdTe core-shell NW arrays as well as their effects on the photovoltaic performances
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
