Researcher(s)
- Abigail Sicher, Engineering Undecided, University of Delaware
Faculty Mentor(s)
- William Shafarman, Material Science and Engineering, University of Delaware
Abstract
Solar energy is a renewable resource that reduces greenhouse emissions and mitigates the harmful effects of climate change. The leading commercial solar cells are made of crystalline silicon, but they can be costly and complicated to manufacture. Cadmium telluride (CdTe) solar cells show promise for affordability once the efficiency of thin-film cells improves. These cells require less material for absorption than other solar cell technologies, thereby lowering manufacturing costs. Zinc alloying is being used in CdTe cell processing to improve optical properties. However, current post-treatment processing interferes with these beneficial effects. The current CdTe process involves various heat treatments and film depositions, with a final post-treatment using cadmium chloride (CdCl2) performed to improve the material quality. My project specifically involves developing a new post-treatment using antimony chloride (SbCl3) to create a procedure compatible with cadmium zinc telluride (CdZnTe). The process I developed takes a CdTe cell and drips an SbCl2 solution in methanol on the surface, then the cell undergoes annealing in a tube oven. The experimentation aspect involves varying the concentration of SbCl3, temperatures, and time of heat treatment. To quantitatively compare these cells, I measure the power conversion of light to electricity, and qualitatively I compare the surface appearance and grain shape/size with a scanning electron microscope. Initial results show evidence of improved light-to-electricity power conversion between cells with the SbCl3 post-treatment versus those with no post-treatment. The efficiency of the SbCl3 cells shows promise of eventually meeting the efficiency levels of CdCl2 post-treated cells. More experimentation must be done to optimize SbCl3 treatments. In the field of solar energy, a successful SbCl3 post-treatment allows us to use zinc to improve CdTe efficiency and bring lower costs to solar energy.