Characterization of variable-band-gap thin-film Cu(In,Ga)Se2: a simple model for the interdiffusion of In and Ga in alloy structures

✍ Scribed by John R. Turtle; D.S. Albin; A. Tennant; A.M. Gabor; M. Contreras; R. Noufi

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 437 KB
• Volume: 35
• Category: Article
• ISSN: 0927-0248
• DOI: 10.1016/0927-0248(94)90140-6

✦ Synopsis

Thin-film photovoltaic devices based upon the Cu(In,Ga)Se 2 material system continue to advance with total-area cell efficiencies approaching 16%. Fabrication processes have been developed that may easily be transferred to industrial scale systems. Device designs incorporating variable-band-gap absorbers have been successful in realizing the full potential of the alloy material system. The final In and Ga distribution and phase nature of the variable-band-gap absorber is highly dependent on the fabrication process. A growth model describes the interdiffusion of CulnSe: and CuGaSe2 for three fabrication scenarios. The incorporation of the In and Ga has been accomplished in such a manner that a range of device parameters results. Higher open-circuit voltage devices offer the opportunity for lower interconnect losses at the module level. The highest efficiency device fabricated to date exhibits the following characteristics: area = 0.43 cm 2, Vo~ = 650 mV, Jsc(total-area) = 32.2 mA/cm 2, FF = 76.1%, and '7 = 15.9%. Our work at The National Renewable Energy Laboratory is presently focusing on realizing these improvements, scaling to 100 cm 2 submodule sizes, and transferring the processes to a non-physical vapor deposition equipment systems.