Solar selective coating

A solar absorber, comprising:

• a solar selective coating deposited on a substrate, the solar selective coating including an adhesion layer;
• an absorber stack including at least one absorber layer;
• and an antireflection stack including at least one antireflection layer,
• wherein the adhesion layers, the absorber stack and the antireflection stack are provided in a sandwich construction in which the adhesion layer is deposited on the substrate, the absorber stack is deposited on the adhesion layer, and the antireflection stack deposited on the absorber stack,
• wherein the adhesion layer includes a metallic layer with a refractory metal and a dope-material, the dope-material including a metal or a metalloid, the metallic layer being configured with an amorphous disordered structure, and wherein a surface of the substrate is a pre-polished surface, and the substrate includes at least one high temperature stable metallic alloy;
• and
• wherein the metallic layer includes molybdenum as refractory metal and titanium as dope-material.

A method for making a solar selective coating deposited on a substrate by a vacuum deposition process, comprising:

• providing the substrate which is pre-polished;
• depositing an adhesion layer onto the pre-polished substrate;
• depositing an absorber stack onto the adhesion layer one layer at a time;
• and
• depositing an antireflection stack onto the absorber stack one layer at a time,
• wherein the adhesion layer includes a metallic layer with a refractory metal and a dope-material, the dope-material including a metal or a metalloid;
• wherein the metallic layer is configured with an amorphous disordered structure;
• and
• wherein the metallic layer includes molybdenum as refractory metal and titanium as dope-material.

A method for making a solar selective coating configured to be deposited on a substrate for a vacuum deposition process, comprising:

• ion etching of a surface of the substrate with an ion gun using a process pressure in the range of 1E-5 bar to 5E-2 bar, and argon gas as an ionization gas;
• providing a temperature of above 100° C. to the substrate;
• sputtering for a deposition of an adhesion layer including a metallic layer that includes molybdenum and titanium using a process pressure in the range of 1E-3 bar to 1E-2 bar, and argon as a sputtering gas;
• sputtering for a deposition of a titanium aluminium nitride layer using a process pressure in the range of 1E-3 to bar 1E-2 bar, argon as the sputtering gas, and nitrogen as a reactive gas using a partial pressure of the reactive gas in the range of 1E-6 to 5E-4 mbar;
• and
• sputtering for a deposition of at least one silicon nitride layer using a process pressure in the range of 1E-3 bar to 1E-2 bar, argon as the sputtering gas, and nitrogen as the reactive gas using a partial pressure of the reactive gas in the range of 1E-6 to 5E-4 mbar wherein:
• the solar selective coating further including (a) an absorber stack including at least one absorber layer, and (b) an antireflection stack comprising at least one antireflection layer, wherein the adhesion layer, the absorber stack and the antireflection stack are provided in a sandwich construction in which the adhesion layer is deposited on the substrate, the adhesion layer has a 110-130 nm thickness, the adhesion layer including a metallic layer with 85-99% (w/w) Mo and 1-15% (w/w) Ti, the absorber stack configured with a single absorber layer including a 110-130 nm titanium aluminium nitride layer, and the antireflection stack configured with a single antireflection layer including at least one 50-70 nm silicon nitride layer.

A method for making a solar selective coating configured to be deposited on a substrate for a vacuum deposition process, comprising:

• ion etching of a surface of the substrate with an ion gun using a process pressure in the range of 1E-5 bar to 5E-2 bar, and argon gas as an ionization gas;
• providing a temperature of above 100° C. to the substrate;
• sputtering for a deposition of an adhesion layer including a metallic layer that includes molybdenum and titanium using a process pressure in the range of 1E-3 bar to 1E-2 bar, and argon as a sputtering gas;
• sputtering for a deposition of a titanium aluminium nitride layer using a process pressure in the range of 1E-3 to bar 1E-2 bar, argon as the sputtering gas, and nitrogen as a reactive gas using a partial pressure of the reactive gas in the range of 1E-6 to 5E-4 mbar;
• and
• sputtering for a deposition of at least one silicon nitride layer using a process pressure in the range of 1E-3 bar to 1E-2 bar, argon as the sputtering gas, and nitrogen as the reactive gas using a partial pressure of the reactive gas in the range of 1E-6 to 5E-4 mbar wherein:
• the solar selective coating further including (a) an absorber stack including at least one absorber layer, and (b) an antireflection stack including at least one antireflection layer, wherein the adhesion layer, the absorber stack and the antireflection stack are provided in a sandwich construction in which the adhesion layer is deposited on the substrate, the adhesion layer includes a 110-130 nm thickness, the adhesion layer including a metallic layer with 85-99% (w/w) Mo and 1-15% (w/w) Ti, the absorber stack is configured with a single absorber layer including a 60-80 nm titanium aluminium nitride layer, and a single semi-absorber layer including a 20-40 nm titanium aluminium oxynitride layer, and the antireflection stack is configured with a single antireflection layer including at least one 70-90 nm silicon oxide layer.

A process for providing a solar absorber by depositing a solar selective coating via a vacuum deposition process onto a thermal absorber configuration, comprising:

• providing a pre-polished substrate;
• preparing a surface of the substrate by ion-etching;
• depositing an adhesion layer onto the substrate surface;
• depositing an absorber stack onto the adhesion layer one layer at a time;
• and depositing an antireflection stack onto the absorber stack one layer at a time, wherein the adhesion layer includes a metallic layer including a refractory metal and a dope-material, the dope-material including a metal or metalloid, the metallic layer being configured with an amorphous disordered structure;
• and
• wherein the metallic layer includes molybdenum as refractory metal and titanium as dope-material.