PHOTOVOLTAICS WITH INTERFEROMETRIC BACK SIDE MASKS
An interferometric mask covers reflective conductors on the back side of a photovoltaic device. Such an interferometric mask may reduce reflections of incident light from the conductors. In various embodiments, the mask reduces reflections, so that a front and back electrode pattern appears black or similar in color to surrounding features of the device. In other embodiments, the mask may modulate reflections of light such that the electrode pattern matches a color in the visible spectrum.
1 . A photovoltaic device defining a front side on which light is incident and a back side opposite the front side, the photovoltaic device comprising:
a photovoltaic active material;
a conductor on the back side of the photovoltaic material; and
an optical interferometric mask over the back side of the conductor.
2 . The photovoltaic device of claim 1 , wherein the optical interferometric mask is configured such that a color of light reflected from the mask substantially matches a color of surrounding features on the back side of the photovoltaic device.
3 . The photovoltaic device of claim 2 , wherein the optical interferometric mask is configured such that the color of light reflected from the mask substantially matches a color in the visible spectrum.
4 . The photovoltaic device of claim 1 , wherein the light reflected from the optical interferometric mask falls within the wavelengths associated with the visible spectrum.
5 . The photovoltaic device of claim 1 , wherein the optical interferometric mask is configured such that little or no incident visible light is reflected from the back side of the interferometric mask such that the interferometric mask appears black from a normal viewing angle.
6 . The photovoltaic device of claim 1 , wherein the optical interferometric mask is configured such that the reflectivity in the visible range from the mask is less than 10%.
7 . The photovoltaic device of claim 1 , wherein the optical interferometric mask comprises:
a reflective surface;
an optical resonant cavity over the back of the reflective surface; and
an absorber over the back of the optical resonant cavity.
8 . The photovoltaic device of claim 7 , wherein the reflective surface is defined by a separate metallic reflector layer between the conductor and the optical resonant cavity.
9 . The photovoltaic device of claim 7 , wherein the reflective surface is defined by the back surface of the conductor.
10 . The device of claim 1 , wherein the photovoltaic device is incorporated into a window.
11 . The photovoltaic device of claim 1 , further comprising:
a display;
a processor that is configured to communicate with said display, said processor being configured to process image data; and
a memory device that is configured to communicate with said processor.
12 . The photovoltaic device as recited in claim 11 , further comprising:
a driver circuit configured to send at least one signal to said display.
13 . The photovoltaic device as recited in claim 12 , further comprising:
a controller configured to send at least a portion of said image data to said driver circuit.
14 . A photovoltaic device comprising:
means for generating an electrical current from incident light on a side of said means;
front side means and back side means for conducting the generated electrical current; and
means for interferometrically masking said back side conducting means from the incident side of the photovoltaic device.
15 . A method of manufacturing a photovoltaic device, comprising
providing a photovoltaic generator with a photovoltaic active layer, a front side conductor and a back side conductor, the front side conductor configured to allow light through the front side to the photovoltaic active layer; and
forming a plurality of layers over the back side conductor of the photovoltaic generator to define an interferometric modulator configured to mask the back side conductor.
16 . The method of claim 15 , wherein the interferometric modulator is integrated with the back side of the photovoltaic device.
17 . The method of claim 16 , wherein the interferometric modulator is deposited across the back side conductor.
18 . The method of claim 17 , wherein the interferometric modulator extends beyond the surface of the back side conductor by less than about 10%.
19 . The method of claim 18 , wherein the interferometric modulator extends beyond the surface of the back side conductor by less than about 5%.
20 . The method of claim 15 , wherein the interferometric modulator is patterned across the back side conductor.
21 . The method of claim 20 , wherein the interferometric modulator comprises an absorber, an optical resonant cavity, and a conductor, wherein the absorber is patterned to follow a pattern of the back side conductor.
22 . The method of claim 21 , wherein the optical resonant cavity is patterned to follow a pattern of the back side conductor.
23 . The method of claim 21 , wherein the absorber and optical resonant cavity are configured to reflect visible light substantially matching a visible spectrum reflected by exposed portions of the photovoltaic device.
24 . A method of manufacturing a photovoltaic device having a front side on which light is incident and a back side opposite the front side, the method comprising forming an interferometric modulator configured to reduce visible reflections from the back side of the photovoltaic device.
25 . The method of claim 24 , wherein the interferometric modulator interferometrically produces a black appearance.
26 . The method of claim 24 , wherein the interferometric modulator interferometrically produces a coherent color in the visible spectrum.