Method for making composite article comprising oriented microstructures

Abstract

This invention provides a composite article having discrete microstructures partially encapsulated within a layer. A method of making the same is also provided. The article of the present invention is useful for visible radiation absorbing devices, such as, for example, selective solar absorbers, flat plate solar collectors, solar absorption panels, and solar cells.

I claim: 
     
       1. A method for making a composite article comprising a layer having a dense array of discrete microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said microstructures and a surface of said layer are on a common side of said layer, said method comprising the steps of: (a) providing a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said microstructured-layer comprises a dense array of discrete microstructures directly on said surface of said substrate, wherein said microstructures are selected from the group consisting of organic microstructures, and inorganic semiconductor microstructures, and wherein said microstructures have a mean diameter in the range from about 1 to about 5000 nanometers; and   (b) delaminating said encapsulated microstructured-layer from said substrate to provide said composite article.   
     
     
       2. The method according to claim 1 wherein said exposed distal ends of said microstructures and said surface of said layer are on a common plane. 
     
     
       3. The method according to claim 1, wherein said substrate bearing an encapsulated microstructured-layer is provided by the steps of: i) depositing a sufficient amount of an organic material as a layer onto a substrate to provide a deposited organic layer such that after step (ii) a microstructured-layer comprising a dense array of discrete microstructures is formed;   ii) annealing said deposited organic layer in a vacuum for a time and at a temperature sufficient to induce a physical change in said deposited organic layer to form a microstructured-layer comprising a dense array of discrete microstructures; and   iii) encapsulating said microstructured-layer with at least one encapsulating material.   
     
     
       4. The method according to claim 3 wherein said layer is deposited by a technique selected from the group consisting of vapor phase deposition, dispersion coating, and solution coating. 
     
     
       5. The method according to claim 3 further comprising the step of conformal coating said microstructured-layer with at least one coating material prior to encapsulation step iii. 
     
     
       6. The method according to claim 5 wherein said conformal coating is deposited by a technique selected from the group consisting of vapor phase coating, dispersion coating, and solution coating. 
     
     
       7. The method according to claim 3 wherein step (i) includes heating said substrate. 
     
     
       8. The method according to claim 1 wherein said encapsulating material is coated over said microstructured-layer by a technique selected from the group consisting of vapor phase deposition, solution coating, dispersion coating, and solid-liquid deposition. 
     
     
       9. The method according to claim 5 wherein said conformal coating comprises at least one of an organic material or an inorganic material. 
     
     
       10. The method according to claim 9 wherein said inorganic material of said conformal coating is selected from the group consisting of metal oxides, metal sulfides, metal chlorides, metal carbides, metal borides, metal nitrides, metal silicides, and metals. 
     
     
       11. The method according to claim 9 wherein said organic material of said conformal coating is a polymeric material. 
     
     
       12. The method article according to claim 1 wherein said microstructures have an areal number density in the range from about 1 to about 10 4  microstructures per square micrometer. 
     
     
       13. The method according to claim 1 wherein said inorganic semiconductor microstructures comprise a material selected from the group consisting of diamond, germanium, selenium, arsenic, silicon, tellurium, gallium arsenide, gallium antimonide, gallium phosphide, aluminum antimonide, indium antimonide, indium tin oxide, zinc antimonide, indium phosphide, aluminum gallium arsenide, zinc teluride, and combinations thereof. 
     
     
       14. The method according to claim 5 wherein said conformal coating is deposited by a technique selected from the group consisting of vapor phase deposition and solution coating. 
     
     
       15. The method according to claim 1 wherein each of said microstructures comprises polycrystalline regions. 
     
     
       16. The method according to claim 1 wherein said organic microstructures comprise organic material, wherein said organic material has planar molecules comprising chains or rings over which II-electron density is delocalized. 
     
     
       17. The method according to claim 16 wherein said organic material is selected from the group consisting of perylenes, phthalocyanines, and porphyrins. 
     
     
       18. The method according to claim 1 wherein said encapsulating material is selected from the group consisting of an organic material and an inorganic material. 
     
     
       19. The method according to claim 1 wherein said microstructures are essentially uniform in size and shape. 
     
     
       20. The method according to claim 1 wherein said microstructures have an aspect ratio which ranges from about 3:1 to about 100:1. 
     
     
       21. The method for making a composite article comprising a layer having a dense array of discrete ceramic microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said ceramic microstructures and a surface of said layer are on a common side of said layer, said method comprising the steps of: (a) providing a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said microstructured-layer comprises a dense array of discrete ceramic microstructures directly on said surface of said substrate, wherein said ceramic microstructures have a mean diameter in the range from about 1 to about 5000 nanometers; and   (b) delaminating said encapsulated microstructured-layer from said substrate to provide said composite article.   
     
     
       22. A method for making a composite article comprising a layer having a dense array of discrete, regularly arrayed, organic microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said microstructures and a surface of said layer are on a common side of said layer, said method comprising the steps of: (a) providing a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said microstructured-layer comprises a dense array of discrete, regularly arrayed, organic microstructures directly on said surface of said substrate; and   (b) delaminating said encapsulated microstructured-layer from said substrate to provide said composite article.   
     
     
       23. The method according to claim 22 wherein said organic microstructures are essentially uniform in size and shape. 
     
     
       24. The method according to claim 23 wherein said organic microstructures have an aspect ratio in the range from about 3:1 to about 100:1. 
     
     
       25. The method according to claim 24 wherein said organic microstructures have a mean diameter in the range from about 1 to about 5000 nanometers. 
     
     
       26. A method for making a composite article comprising a layer having a dense array of discrete organic microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said microstructures and a surface of said layer are on a common side of said layer, wherein interposed between said organic microstructures and said encapsulant is a conformal coating of an inorganic conformal coating material, said method comprising the steps of: (a) providing a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said encapsulated microstructured-layer comprises a dense array of discrete microstructures directly on said surface of said substrate, an encapsulant, and a conformal coating of an inorganic conformal coating material interposed between said microstructures and said encapsulant; and   (b) delaminating said encapsulated microstructured layer from said substrate to provide said composite article.   
     
     
       27. A method for making a composite article comprising a layer having a dense array of discrete microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said microstructures and a surface of said layer are on a common side of said layer, said method comprising the steps of: (a) providing a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said microstructured-layer comprises a dense array of discrete microstructures directly on said surface of said substrate, and wherein said microstructures have a mean diameter in the range from about 1 to about 1000 nanometers .Iadd.and an aspect ratio in the range from about 3:1 to about 100:1.Iaddend.; and   (b) delaminating said encapsulated microstructured-layer from said substrate to provide said composite article.   
     
     
       28. A method for making a composite article comprising a layer having a dense array of discrete metal microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said microstructures and a surface of said layer are on a common side of said layer, said method comprising the steps of: (a) providing a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said microstructured-layer comprises a dense array of discrete metal microstructures directly on said surface of said substrate, and wherein said microstructures have a mean diameter in the range from about 1 to about 5000 nanometers .Iadd.and an aspect ratio in the range from about 3:1 to about 100:1.Iaddend.; and   (b) delaminating said encapsulated microstructured-layer from said substrate to provide said composite article.   
     
     
       29. A method for making a composite article comprising a layer having a dense array of discrete microstructures partially encapsulated therein by an encapsulant, wherein one distal end of each of said microstructures is exposed, and wherein said exposed distal ends of said microstructures and a surface of said layer are on a common side of said layer, said method comprising the steps of: (a) providing a composite article comprising a substrate bearing an encapsulated microstructured-layer, wherein said substrate has a surface, wherein said microstructured-layer comprises a dense array of discrete microstructures directly on said surface of said substrate, wherein said microstructures are essentially uniform in size and shape, wherein said microstructures have an aspect ratio in the range from about 3:1 to about 100:1, and wherein said microstructures have a mean diameter in the range from about 1 to about 1000 nanometers; and   (b) delaminating said encapsulated microstructured-layer from said substrate to provide said composite article.