Thin film Cu(In,Ga)Se2 materials and devices: a versatile material for flat-plate and concentrator photovoltaic applications

John R. Tuttle; M. A. Contreras; J. S. Ward; A. L. Tennant; K. R. Ramanathan; J. Keane; R. N. Noufi

doi:10.1117/12.217333

23 August 1995 Thin film Cu(In,Ga)Se₂ materials and devices: a versatile material for flat-plate and concentrator photovoltaic applications

John R. Tuttle, M. A. Contreras, J. S. Ward, A. L. Tennant, K. R. Ramanathan, J. Keane, R. N. Noufi

Author Affiliations +

Proceedings Volume 2531, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIV; (1995) https://doi.org/10.1117/12.217333
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

Thin-film Cu(In,Ga)Se₂(CIGS) is used as the absorber in an all-thin-film solar cell for both conventional 1-sun and concentrator applications. The absorber fabrication process is represented by time-dependent profiles of elemental Cu, In, Ga, and Se fluxes. The Cu/(In+Ga) ratio determines the phase chemistry during growth whereas the Ga/(Ga+In) ratio determines the CIGS band gap profile. All film-growth processes enter the CIGS:Cu_xSe two-phase field where the Cu_xSe facilitates large grain growth. Characterization of cells under 1-sun illumination reveals world-record total-area performance of 17.1%. Improvements relative to previous cells are linked to decreased inter-diffusion of In and Ga within the absorber. Cell parameters include an open-circuit voltage (V_oc) of 654 mV and short-circuit current (J_sc) of 33.9 mA/cm². A second cell was fabricated for operation under concentration. The 1-sun, direct-spectrum measurement yielded at 15.1%- efficient cell. Under 5- and 22-sun concentration, the cell improved to 16.5% and 17.2%, respectively. This achievement is significant in that it proves a compatibility of polycrystalline thin-film and concentrator technologies. Further optimization could yield 1-sun performance in excess of 18% and concentrator performance in excess of 20%. A path to this goal is outlined.

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John R. Tuttle, M. A. Contreras, J. S. Ward, A. L. Tennant, K. R. Ramanathan, J. Keane, and R. N. Noufi "Thin film Cu(In,Ga)Se₂ materials and devices: a versatile material for flat-plate and concentrator photovoltaic applications", Proc. SPIE 2531, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIV, (23 August 1995); https://doi.org/10.1117/12.217333

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