Ultra-low reflectance broadband omni-directional anti-reflection coating

Abstract

An anti-reflection coating has an average total reflectance of less than 10%, for example less than 5.9% such as from 4.9% to 5.9%, over a spectrum of wavelengths of 400-1100 nm and a range of angles of incidence of 0-90 degrees with respect to a surface normal of the anti-reflection coating. An anti-reflection coating has a total reflectance of less than 10%, for example less than 6% such as less than 4%, over an entire spectrum of wavelengths of 400-1600 nm and an entire range of angles of incidence of 0-70 degrees with respect to a surface normal of the anti-reflection coating.

1 . An anti-reflection coating, wherein the anti-reflection coating has an average total reflectance of less than 10% over a spectrum of wavelengths of 400-1100 nm and a range of angles of incidence of 0-90 degrees with respect to a surface normal of the anti-reflection coating. 
     
     
         2 . The anti-reflection coating of  claim 1 , wherein the anti-reflection coating has an average total reflectance of from 4.9 to 10% over a spectrum of wavelengths of 400-1100 nm and a range of angles of incidence of 0-90 degrees with respect to a surface normal of the anti-reflection coating. 
     
     
         3 . The anti-reflection coating of  claim 1 , comprising at least one porous layer and at least one non-porous layer. 
     
     
         4 . The anti-reflection coating of  claim 3 , wherein the at least one porous layer comprises nano-scale structures or porous silica. 
     
     
         5 . The anti-reflection coating of  claim 3 , wherein the at least one porous layers comprises one or more slanted nanorod layers. 
     
     
         6 . The anti-reflection coating of  claim 5 , wherein:
 the one or more slanted nanorod layers comprises at least a first slanted nanorod layer and a second slanted nanorod layer located over the first slanted nanorod layer;   the first slanted nanorod layer has a first porosity; and   the second slanted nanorod layer has a second porosity greater than the first porosity.   
     
     
         7 . The anti-reflection coating of  claim 6 , wherein:
 the first slanted nanorod layer comprises nanorods slanted in a first direction; and   the second slanted nanorod layer comprises nanorods slanted in a second direction different from the first direction.   
     
     
         8 . The anti-reflection coating of  claim 6 , further comprising a barrier layer located between the first slanted nanorod layer and the second slanted nanorod layer. 
     
     
         9 . The anti-reflection coating of  claim 8 , wherein the barrier layer is transparent and chemically resistive. 
     
     
         10 . The anti-reflection coating of  claim 5 , wherein:
 the one or more slanted nanorod layers comprise nanorods made of at least one of silicon oxide, titanium oxide, silicon oxynitride, aluminum oxide, zinc oxide, transparent organic materials, or combinations thereof;   each of the one or more slanted nanorod layers has a thickness of 20 nm to 500 nm; and   the one or more slanted nanorod layers having a porosity from 10% to 90%   
     
     
         11 . The anti-reflection coating of  claim 5 , wherein:
 the one or more slanted nanorod layers comprise nanorods made of at least one of silicon oxide, titanium oxide, silicon oxynitride, aluminum oxide, zinc oxide, transparent organic materials, or combinations thereof;   each of the one or more slanted nanorod layers has a thickness of 20 nm to 100 nm; and   the nanorods have a tilt angle of 0 to 60 degrees with respect to surface normal.   
     
     
         12 . The anti-reflection coating of  claim 3 , wherein:
 the anti-reflection coating comprises at least three layers having index of refraction values that vary discretely from about 3.6 to about 1; and   an index of refraction profile of the anti-reflection coating has an approximate Gaussian or Quintic distribution and is smooth to a first derivative and a second derivative.   
     
     
         13 . The anti-reflection coating of  claim 3 , wherein:
 the anti-reflection coating comprises at least three layers having index of refraction values that vary discretely from about 2.6 to about 1.09; and   an index of refraction profile of the anti-reflection coating has an approximate Gaussian or Quintic distribution and is smooth to a first derivative and a second derivative.   
     
     
         14 . The anti-reflection coating of  claim 3 , wherein:
 the anti-reflection coating has a continuous index of refraction profile varying from about 3.6 to about 1; and   the index of refraction profile has an approximate Gaussian or Quintic distribution.   
     
     
         15 . The anti-reflection coating of  claim 3 , wherein:
 the anti-reflection coating has a continuous index of refraction profile varying from about 2.6 to about 1.09; and   the index of refraction profile has an approximate Gaussian or Quintic distribution.   
     
     
         16 . The anti-reflection coating of  claim 3 , wherein:
 the at least one non-porous layer has an index of refraction of greater than 1.5; and   the at least one porous layer has an index of refraction of 1.1 to 1.25 and a porosity of 90-95%.   
     
     
         17 . The anti-reflection coating of  claim 1 , wherein:
 the anti-reflection coating has a total thickness of 1-5 optical wavelengths;   the anti-reflection coating comprises at least three layers; and   each of the at least three layers has a thickness of around 100 nm or less.   
     
     
         18 . A solar cell, comprising:
 a first electrode located over a substrate;   at least one photovoltaic layer located over the first electrode;   a second electrode located over the at least one photovoltaic layer; and   the anti-refection coating according to  claim 1  located over the second electrode.   
     
     
         19 . (canceled) 
     
     
         20 . An anti-reflection coating, wherein the anti-reflection coating has a total reflectance of less than 10% over an entire spectrum of wavelengths of 400-1600 nm and an entire range of angles of incidence of 0-70 degrees with respect to a surface normal of the anti-reflection coating. 
     
     
         21 . The anti-reflection coating of  claim 20 , wherein the anti-reflection coating has a total reflectance of less than 6% over a spectrum of wavelengths of 400-1600 nm and an entire range of angles of incidence of 0-70 degrees with respect to a normal to a surface normal of the anti-reflection coating. 
     
     
         22 - 39 . (canceled) 
     
     
         40 . An anti-reflection coating, comprising:
 one or more titanium oxide layers;   one or more intermixed layers located over the one or more titanium oxide layers; and   one or more slanted nanorod layers, the one or more slanted nanorod layers being located over the one or more intermixed layers.   
     
     
         41 - 54 . (canceled) 
     
     
         55 . An anti-reflection coating located over a substrate, the anti-reflection coating comprising:
 one or more non-porous layers;   a first slanted nanorod layer having a first porosity located over the non-porous layer; and   a second slanted nanorod layer having a second porosity located over the first slanted nanorod layer.   
     
     
         56 . The anti-reflection coating of  claim 55 , wherein:
 the first slanted nanorod layer comprising a first plurality of nanorods slanted in a first direction; and   the second slanted nanorod layer comprising a second plurality of nanorods slanted in a second direction different from the first direction.   
     
     
         57 . The anti-reflection coating of  claim 55 , wherein:
 the first nanorod layer and the second nanorod layer comprise independently at least one of silicon oxide, titanium oxide, silicon oxynitride, aluminum oxide, zinc oxide, transparent organic materials, or combinations thereof;   each of the first and second slanted nanorod layers has a thickness of 20 nm to 500 nm;   the second porosity is greater than the first porosity.   
     
     
         58 . The anti-reflection coating of  claim 55 , wherein:
 the anti-reflection coating further comprises a third slanted nanorod layer having a third porosity located over the second slanted nanorod layer; and   the third porosity is greater than the second porosity.   
     
     
         59 . The anti-reflection coating of  claim 55 , further comprising a barrier layer located between the first slanted nanorod layer and the second slanted nanorod layer. 
     
     
         60 . The anti-reflection coating of  claim 59 , wherein the barrier layer is transparent and chemically resistive. 
     
     
         61 . The anti-reflection coating of  claim 55 , wherein:
 the anti-reflection coating has an index of refraction profile varying discretely from about 3.6 to about 1; and   the index of refraction profile of the anti-reflection coating has an approximate Gaussian or Quintic distribution and is smooth to first derivative and second derivative.   
     
     
         62 - 63 . (canceled) 
     
     
         64 . The anti-reflection coating of  claim 55 , wherein:
 the anti-reflection coating has a continuous index of refraction profile varying from about 2.6 to about 1.09; and   the index of refraction profile has an approximate Gaussian or Quintic distribution.   
     
     
         65 . (canceled) 
     
     
         66 . An anti-reflection coating, comprising:
 a first slanted nanorod layer having a first porosity; and   a second slanted nanorod layer having a second porosity located over the first slanted nanorod layer;   wherein the index of refraction profile of the anti-reflection coating has an approximate Gaussian distribution.   
     
     
         67 - 76 . (canceled) 
     
     
         77 . A method of making an anti-reflection coating, comprising:
 depositing one or more titanium oxide layers;   depositing one or more co-sputtered layers of titanium oxide and silicon oxide over the one or more titanium oxide layers; and   depositing one or more slanted nanorod layers over the one or more co-sputtered layers titanium oxide and silicon oxide.   
     
     
         78 . The method of  claim 77 , wherein the step of depositing one or more slanted nanorod layers comprises:
 depositing a first slanted nanorod layer having a first porosity;   depositing a second slanted nanorod layer having a second porosity located over the first slanted nanorod layer; and   the second porosity is greater than the first porosity.   
     
     
         79 . (canceled) 
     
     
         80 . The method of  claim 78 , wherein:
 the first slanted nanorod layer comprising nanorods slanted in a first direction; and   the second slanted nanorod layer comprising nanorods slanted in a second direction different from the first direction.   
     
     
         81 . The method of  claim 78 , further comprising depositing a barrier layer over the first slanted nanorod layer, prior to the step of depositing the second slanted nanorod layer. 
     
     
         82 . The anti-reflection coating of  claim 81 , wherein the barrier layer is transparent and chemically resistive. 
     
     
         83 . The method of  claim 77 , wherein the step of depositing one or more slanted nanorod layers comprises depositing slanted nanorods with a predetermined tilt angle and porosity by oblique angle deposition. 
     
     
         84 . The method of  claim 77 , wherein:
 during the step of depositing one or more slanted nanorod layers, a plurality of pores are formed between the nanorods; and   during the step of depositing the one or more co-sputtered layers or the step of depositing the one or more titanium oxide layers, substantially no pores are formed.   
     
     
         85 . (canceled) 
     
     
         86 . The method of  claim 77 , wherein an index of refraction profile of the anti-reflection coating is graded and varies from about 3.6 to about 1. 
     
     
         87 . (canceled) 
     
     
         88 . The method of  claim 77 , wherein, during the step of depositing the one or more co-sputtered layers at least one of sputtering parameters varies in real time in such a way that the one or more co-sputtered layers has a continuous composition profile, providing a continuous index of refraction profile. 
     
     
         89 . The method of  claim 77 , further comprising:
 depositing a first electrode located over a substrate;   depositing at least one photovoltaic layer over the first electrode;   depositing a second electrode over the at least one photovoltaic layer, prior to the step of depositing the one or more titanium oxide layers.