A Study of Cadmium Telluride Solar Cell Architecture Optimization and Fabrication Using Highly Order Nano-dome Arrays

Open Access
Author:
Waggoner, Shawn Allen
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Wook Jun Nam, Thesis Supervisor
  • Gary Gray, Honors Advisor
Keywords:
  • solar cell architecture
  • solar
  • LCCM
  • CdTe
  • cadmium
  • telluride
  • numerical modeling
  • engineering
  • engineering science
Abstract:
For solar cells to continue their rise toward being a highly competitive energy source, new designs must show decreases in cost/watt, meaning that solar power conversion efficiency must continue to rise while fabrication costs drop. To make this happen, many researchers have turned to light trapping techniques that improve light absorption while allowing manufacturers to reduce material thickness. The preferred light trapping technique is currently randomized surface texturing, but considering that this approach does not yield consistent device performances, more research is being carried out on periodic surface texturing. To date, Cadmium Telluride solar cells are among the most economic solar cells commercially developed: the material has an ideal band gap for absorbing the solar spectrum, one of the highest maximum power conversion efficiencies of any single junction solar cell absorber, the device fabrication is cheaper than most solar cells designs, and it has a long device lifetime. To further optimize CdTe solar cell design, light trapping techniques employing highly ordered nano-element arrays are now being considered. This thesis is attempting to determine the viability of CdTe solar cells with a textured back electrode and conformal dome layers of material. The periodic structures are compared against corresponding planar structures in a range of CdTe thickness from 250 – 1000nm. Each of the periodically textured CdTe solar cells perform significantly better than their planar peer: achieving improvements in short circuit current density ranging from 9.2 – 14.1%. Of equal importance, the thinnest LCCM CdTe cell (250nm) had a JSC value 1.1mA/cm2 higher than the thickest planar CdTe cell (1000nm). This data demonstrates that LCCM designs are certainly capable of enhancing the performance of single junction CdTe solar cells, and paves the way for research on the fabrication of these cells.