Progress in Polycrystalline Thin-Film Cu(In,Ga)Se2Solar Cells

Abstract

For some time, the chalcopyrite semiconductor CuInSe2and its alloy with Ga and/or S [Cu(InGa)Se2or Cu(InGa)(Se,S)2], commonly referred as CIGS, have been leading thin-film material candidates for incorporation in high-efficiency photovoltaic devices. CuInSe2-based solar cells have shown long-term stability and the highest conversion efficiencies among all thin-film solar cells, reaching 20%. A variety of methods have been reported to prepare CIGS thin film. Efficiency of solar cells depends upon the various deposition methods as they control optoelectronic properties of the layers and interfaces. CIGS thin film grown on glass or flexible (metal foil, polyimide) substrates require p-type absorber layers of optimum optoelectronic properties and n-type wideband gap partner layers to form the p-n junction. Transparent conducting oxide and specific metal layers are used for front and back contacts. Progress made in the field of CIGS solar cell in recent years has been reviewed.

Transparent electrodes for organic optoelectronic devices: a review

“…131,132 Here, microscopic metal grids composed of ordered metal lines that are <1 μm wide are discussed and considered as a potential replacement for semitransparent continuous metal films for use as TEs in organic optoelectronic devices. [133][134][135] One of the advantages of metal grids is the increased transparency compared to continuous metal layers, where the gaps between metal lines are blank (100% in transparency) and contribute to the high transparency.…”

Native point defects in CuIn1−xGaxSe2: hybrid density functional calculations predict the origin of p- and n-type conductivity

“…A similar expression can be derived for donors, for which the Fermi-Dirac-like distribution depends on (E F − ε(+1/0)). To simulate the experiments more closely, we calculate the total concentration of a defect -as a sum of the concentrations due to the different charge states -at 800 K. This is the temperature around which CIGS samples are usually grown, in coevaporation and in vacuum-based sequential growth methods, during selenization 43 . It is likely that the total concentration formed during growth freezes in during cooling down, due to kinetic barriers 10 .…”

Na incorporation into Cu(In,Ga)Se2 thin-film solar cell absorbers deposited on polyimide: Impact on the chemical and electronic surface structure

“…The many diverse effects ascribed to the incorporation of Na in the CIGSe material have been summarized and discussed extensively. [18][19][20][21][22] While making no claim of being complete, the most prominent Na-related effects discussed in the past are:…”