INTERFEROMETRIC MASKS
An interferometric mask covering the front electrodes of a photovoltaic device is disclosed. Such an interferometric mask may reduce reflections of incident light from the electrodes. In various embodiments, the mask reduces reflections so that a front electrode pattern appears similar in color to adjacent regions of visible photovoltaic active material.
1 . A device comprising:
a stack of thin films defining a static interferometric modulator, the stack including:
a reflective conductor;
an absorber; and
an optical resonant cavity between the reflective conductor and the absorber, wherein the optical resonant cavity includes a transparent conducting material.
2 . The device of claim 1 , wherein the transparent conducting material includes indium tin oxide.
3 . The device of claim 1 , wherein the reflective conductor is patterned so as to form a conductive line for carrying current.
4 . The device of claim 3 , wherein the device includes a photovoltaic active layer, and the conductive line forms an electrode on a front side of the photovoltaic active layer.
5 . The device of claim 4 , wherein the absorber is arranged on the front side of the conductive line.
6 . The device of claim 4 , wherein the electrode includes a bus electrode connecting a plurality of photovoltaic cells in an array.
7 . The device of claim 4 , wherein the electrode serves as a gridline electrode.
8 . The device of claim 4 , wherein the static interferometric modulator is configured such that a color of light reflected from the front side of the static interferometric modulator substantially matches a color of the photovoltaic active layer visible in regions adjacent the reflective conductor.
9 . The device of claim 3 , wherein the absorber is patterned to follow and cover the reflective conductor.
10 . The device of claim 9 , wherein the absorber is patterned to have a width coextensive with a width of the reflective conductor.
11 . The device of claim 9 , wherein the optical resonant cavity is patterned to follow and cover the reflective conductor.
12 . The device of claim 11 , wherein the optical resonant cavity and absorber are each patterned to be wider than the conductive line.
13 . The device of claim 1 , wherein the static interferometric modulator is configured such that little or no incident visible light is reflected from a front side of the static interferometric modulator and the static interferometric modulator appears black from a normal viewing angle.
14 . The device of claim 1 , wherein the static interferometric modulator is configured such that the reflectivity of the static interferometric modulator is less than 10%.
15 . The device of claim 1 , wherein the absorber includes a semitransparent thickness of metallic or semiconductor layers.
16 . The device of claim 1 , wherein the absorber includes at least one of: chromium, molybdenum, titanium, silicon, tantalum, and tungsten.
17 . The device of claim 1 , wherein the absorber is formed on a substrate, the optical resonant cavity is formed on the absorber, and the reflective conductor is formed on the optical resonant cavity.
18 . A method of manufacturing a device, the method comprising:
depositing an absorber on a substrate;
forming an optical resonant cavity over the absorber, wherein the optical resonant cavity includes a transparent conducting material;
disposing a reflective conductor over the optical resonant cavity; and
patterning the reflective conductor.
19 . The method of claim 18 , wherein the transparent conducting material includes indium tin oxide.
20 . The method of claim 18 , further comprising patterning the optical resonant cavity and the absorber.
21 . The method of claim 20 , wherein the optical resonant cavity and the absorber are patterned to follow the pattern of the reflector.
22 . The method of claim 21 , wherein patterning the reflective conductor includes defining the reflective conductor with a lithographic mask, and wherein the optical resonant cavity and absorber are patterned together with the reflective conductor.