Fabrication of Solar Cells By Tuning the Composition Ratio of AgGaTe2 to Ga-Rich

Abstract Silver gallium telluride (AgGaTe 2 ), an environmentally friendly material with a high optical absorption coefficient, was fabricated by the close-spaced sublimation (CSS) method. It was found that stoichiometric AgGaTe 2 thin films can be produced by using GaTe as the source material for CSS and controlling the Ga molar concentration. Solar cells based on Cu(In, Ga)Se 2 (CIGS), which has a similar structure to that of AgGaTe 2 , have been reported to exhibit conversion efficiencies greater than 20% when the CIGS film is Ga-rich and Cu-poor. By increasing the diffusion/sublimation time during the formation of AgGaTe 2 layers and using source materials with a Ga-rich composition, Ga-enriched AgGaTe 2 thin films were formed. Optimal Ga-rich AgGaTe 2 thin films were produced with extended diffusion/sublimation time, with a Ga mole fraction of 32%. However, Ga-rich Ag-Ga-Te compounds, AgGa 5 Te 8 or Ga 2 Te 3 were developed. Solar cells containing Ga-rich AgGaTe 2 films displayed improved current density–voltage characteristics and spectral sensitivity compared with those of cells containing stoichiometric AgGaTe 2 films. Under AM 1.5 irradiation, the conversion efficiency of the solar cells was recorded at 1.21%.