Cu(In,Ga)(Se,S)₂solar cell research in Solar Frontier: Progress and current status

Abstract

As the largest manufacturer of Cu(In,Ga)(Se,S)2 (CIGS) thin-film photovoltaic modules with more than 1 GW/year production volume, Solar Frontier K.K. has continuously improved module performance and small-area cell efficiencies in the laboratory. Because of our low-cost and environmentally-friendly process, Solar Frontier’s CIGS is a promising technology for the mass production of photovoltaic modules to fill ever-increasing demand. Recently we have achieved certified efficiencies of 22.3 and 22.0% on CdS-buffered and Cd-free buffered small-area cells, respectively, as well as 18.6% on a Cd-free mini-module. In this paper, a review of our CIGS technology and recent progress on the development of the module and the small-area cell is presented.

Single-crystal Cu(In,Ga)Se2solar cells grown on GaAs substrates

“…The GGI was calculated to be 0.6 using Eqs. (1) and (2). We confirmed that the GGI agreed well with the chemical element compositions by electron probe microanalyzer (EPMA) and XRD.…”

“…[1][2][3][4][5][6][7] CIGS solar cells have recently shown conversion efficiencies exceeding 22 and 19.8% for small-area cells (0.5 or 1.0 cm 2 ) [8][9][10] and submodules (24 cm 2 ), 11) respectively. However, almost all CIGS solar cells are based on polycrystalline CIGS layers deposited on soda lime glass (SLG) substrates by a three-stage method 12) or by the selenization and sulfurization of metal precursors.…”

“…However, almost all CIGS solar cells are based on polycrystalline CIGS layers deposited on soda lime glass (SLG) substrates by a three-stage method 12) or by the selenization and sulfurization of metal precursors. 2,11) High-quality singlecrystal CIGS layers have the potential for increasing the efficiency of CIGS solar cells, since there are no grain boundaries and the sharp interface reduces the number of carrier recombination centers. And single crystals are an ideal structure for investigating the effects of alkaline metal incorporations and device physics of CIGS solar cells.…”

From 20.9 to 22.3% Cu(In,Ga)(S,Se)2solar cell: Reduced recombination rate at the heterojunction and the depletion region due to K-treatment

“…Lastly, MgF 2 was deposited as an anti-reflection coating by evaporation. 13) For device characterizations, the J-V curves were measured with class AAA solar simulator WXS-350S-L2MS (Wacom) under the standard test condition (STC). The J-V curve was fitted with one-diode model utilizing Lambert-W function to extract the device parameters, 17) which includes the ideality factor (n L ), series resistance (R s ), shunt resistance (R sh ), and reverse saturation current density (J 0 ).…”

Deposition Technologies of High-Efficiency CIGS Solar Cells: Development of Two-Step and Co-Evaporation Processes

“…In addition, a low-temperature pulsed electron deposition method for the growth of CIGS films was reported, by which a conversion efficiency of 17.0% for the CIGS solar cell was obtained [10]. Among various deposition methods, the two-step and co-evaporation processes have been widely employed for mass production of the large-scale CIGS-based modules [11,12]. Another favorite approach in CIGS industry is the rapid thermal process (RTP), in which a thin Se layer is first capped on the top of metal precursors, CuInGa compounds, and then the diluted H 2 S gas is supplied to simultaneously sulfurize and selenize the precursors to form the Cu(In,Ga)(S,Se) 2 (CIGSS) films in an RTP furnace [13].…”