TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Coating: The anti-reflection coating has an average total reflectance of 4.9-10% 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. The anti-reflection coating has a total reflectance of less than 6 (preferably less than 4)% 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. The coating comprises at least one porous layer and at least one non-porous layer. The coating further comprises a barrier layer located between the first slanted nanorod layer and the second slanted nanorod layer. The coating comprises at least three layers having index of refraction values that vary discretely from 3.6-1 or from 2.6-1.09; 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. The coating has a continuous index of refraction profile of 3.6-1 or 2.6-1.09; and the index of refraction profile has an approximate Gaussian or Quintic distribution. The coating has a total thickness of 1-5 optical wavelengths; and the anti-reflection coating comprises at least three layers; and each of the at least three layers has a thickness of around less than or equal to 100 nm. The anti-reflection coating, comprises: at least one titanium oxide layer; at least one intermixed layer located over the at least one titanium oxide layer; and at least one slanted nanorod layer located over the at least one intermixed layer. The anti-reflection coating located over a substrate, comprises: at least one non-porous layer; 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. The 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. The anti-reflection coating, comprises: 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; where the index of refraction profile of the anti-reflection coating has an approximate Gaussian distribution. Preferred Method: The step of depositing at least one slanted nanorod layer involves: 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; and further involves depositing a third slanted nanorod layer having a third porosity greater than the second porosity. The method further involves depositing a barrier layer over the first slanted nanorod layer, prior to the step of depositing the second slanted nanorod layer. The step of depositing at least one slanted nanorod layer involves depositing slanted nanorods with a predetermined tilt angle and porosity by oblique angle deposition. During the step of depositing at least one slanted nanorod layer, several pores are formed between the nanorods; and during the step of depositing the at least one co-sputtered layer or the step of depositing the at least one titanium oxide layer, substantially no pores are formed. During the step of depositing the at least one co-sputtered layer at least one of sputtering parameters varies in real time in such a way that the at least one co-sputtered layer has a continuous composition profile, providing a continuous index of refraction profile. The method further involves: 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 least one titanium oxide layer. Preferred Components: At least one porous layer comprises nano-scale structures or porous silica. At least one porous layer comprises at least one slanted nanorod layer. At least one slanted nanorod layer 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. 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. The barrier layer is transparent and chemically resistive. At least one slanted nanorod layer comprises nanorods made of at least one of silicon oxide, titanium oxide, silicon oxynitride, aluminum oxide, zinc oxide and/or transparent organic materials; each of the at least one slanted nanorod layer has a thickness of 20-500 nm; and the at least one slanted nanorod layer having a porosity of 10-90%. Each of the at least one slanted nanorod layer has a thickness of 20-100 nm; and the nanorods have a tilt angle of 0-60 degrees with respect to surface normal. 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 1.1-1.25 and a porosity of 90-95%. At least one of the at least one intermixed layer comprises co-sputtered titanium oxide and silicon oxide. At least one titanium oxide layer is non-porous and comprise a titanium oxide layer; the at least one intermixed layer is non-porous and comprises a co-sputtered layer of silicon oxide (63%) and titanium oxide (37%); the second intermixed layer comprises a second composition of silicon oxide and titanium oxide and has a porosity of 19%; the first slanted nanorod layer has a porosity of 71%; and the second slanted nanorod layer has a porosity of 90%. At least one titanium oxide layer is non-porous and comprises at least a first titanium oxide layer, and a second titanium oxide layer located over the first titanium oxide layer; the at least one intermixed layer is non-porous and comprises at least a first intermixed layer having a first composition and a second intermixed layer having a second composition different from the first composition located over the first intermixed layer; 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. The first titanium oxide layer has an index of refraction of around 2.6; the second titanium oxide layer has an index of refraction of 2.52; the first intermixed layer comprises a first composition of silicon oxide and titanium oxide and has an index of refraction of 2.24; the second intermixed layer comprises a second composition of silicon oxide and titanium oxide and has an index of refraction of 1.86; the first slanted nanorod layer has an index of refraction of 1.72; and the second slanted nanorod layer has an index of refraction of 1.09.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Cell: The solar cell further comprises a protective layer located over the anti-reflection coating or between the anti-reflection coating and the second electrode. EXAMPLE - No suitable example given.