:Copper indium gallium selenide

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| ImageFile = Chalcopyrite-unit-cell-3D-balls.png

| ImageCaption = CIGS unit cell. Red = Cu, yellow = Se, blue = In/Ga

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|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|

chemspider}}

| ChemSpiderID = 24774055

| InChI =

| InChIKey =

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI =

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey =

| CASNo = 12018-95-0

| CASNo_Ref = (CuInSe₂)

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|Section2={{Chembox Properties

| Formula =CuIn_1−xGa_xSe₂

| MolarMass =

| Appearance =

| Density = ~5.7 g/cm³

| Solubility =

| MeltingPtC = 1070 to 990

| MeltingPt_notes = (x = 0–1)

| BoilingPt =

| BandGap = 1.0–1.7 eV (x = 0–1)

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|Section3={{Chembox Structure

| MolShape =

| CrystalStruct =tetragonal, Pearson symbol tI16 {{cite journal |doi=10.1002/pssa.2211240206 |title=Phase Diagram and Optical Energy Gaps for CuIn_yGa_1−ySe₂ Alloys |year=1991 |last1=Tinoco |first1=T. |last2=Rincón |first2=C. |last3=Quintero |first3=M. |last4=Pérez |first4=G. Sánchez |journal=Physica Status Solidi A |volume=124 |issue=2 |pages=427 |bibcode=1991PSSAR.124..427T}}

| SpaceGroup = I{{overline|4}}2d

| LattConst_a = 0.56–0.58 nm (x = 0–1)

| LattConst_c = 1.10–1.15 nm (x = 0–1)

| Coordination =

| Dipole =

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Copper indium gallium (di)selenide (CIGS) is a I-III-VI₂ semiconductor material composed of copper, indium, gallium, and selenium. The material is a solid solution of copper indium selenide (often abbreviated "CIS") and copper gallium selenide. It has a chemical formula of CuIn_1−xGa_xSe₂, where the value of x can vary from 0 (pure copper indium selenide) to 1 (pure copper gallium selenide). CIGS is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure, and a bandgap varying continuously with x from about 1.0 eV (for copper indium selenide) to about 1.7 eV (for copper gallium selenide).