Patent Application
20100206370
The present disclosure relates generally to photovoltaic cells. More specifically, the present disclosure relates to reducing light obstruction by using through silicon vias.
Conventional solar cells receive energy from a light source such as the sun, and convert the energy into electricity. Conventional solar cells generally include a photovoltaic layer that receives light photons and converts those photons into electricity. To enhance efficiency, a conductive electrode layer such as one made of Indium-Tin-Oxide, with an irregular surface has been used to deflect more photons into the photovoltaic layer. In such an arrangement, metallic traces are positioned on top of the electrode layer on one side and a metallic layer is positioned on the other side of the photovoltaic layer. A load connected between the metallic traces on the one side and the metallic layer on the other side of the photovoltaic layer provides a conduction path for the generated electricity. In such an arrangement, the metallic traces, being on the light receiving side of the photovoltaic cell, will obstruct some light from entering into the photovoltaic layer and hence will reduce the efficiency of the solar cell.
One way to increase efficiency has been to reduce the size of the metallic traces so that more photons enter the photovoltaic layer. However, reducing the trace size also increases internal resistance of the solar cell, thus reducing efficiency. Another solution has been to reduce the thickness of the electrode layer without decreasing the size of the metallic traces to reduce the amount of light absorbed by the electrode layer. However, the reduced thickness of the electrode layer causes increased internal resistance and the light continues to be obstructed by the metallic traces.
Thus, what is needed is a photovoltaic cell structure that will reduce the obstruction of light to the photovoltaic cell from the metallic traces and thereby increase the efficiency of the photovoltaic cell without increasing the internal resistance of the photovoltaic cell.
In one embodiment, a photovoltaic cell includes a photovoltaic layer with a first node and a second node. A first conductive layer is electrically coupled to the second node of the photovoltaic layer. A second conductive layer is positioned adjacent to but electrically insulated from the first conductive layer on the second node of the photovoltaic layer, so that the second conductive layer will not block light impinging on the first node of the photovoltaic layer. At least one through silicon via is electrically coupled from the first node of the photovoltaic layer to the second conductive layer, with the through silicon via passing through but electrically insulated from the body of the photovoltaic layer and the first conductive layer.
In another embodiment, a light refracting layer can be coupled to the first node of the photovoltaic layer to deflect light into the photovoltaic layer. However, because the through silicon via is electrically coupled directly to the first node, the light refracting layer does not need to be an electrode layer and does not need to be conductive and therefore can have a structure that reduces light absorption without increasing the internal resistance.
In still another embodiment, an apparatus for reducing obstruction of light to a photovoltaic cell includes a means for receiving light and absorbing the light to generate electricity between polarized nodes. A first means for conducting electricity from a first polarized node of the light receiving means while not blocking light from the light receiving means is also included. Finally, a second means for conducting electricity from a second polarized node of the light receiving means while not blocking light from the light receiving means is included in the apparatus.
In yet another embodiment, a method of reducing blocked light to a solar cell includes positioning a photovoltaic layer having a first node and a second node. A first conductive layer is then positioned adjacent to and electrically coupled to the second node of the photovoltaic layer so the first conductive layer does not block light from the photovoltaic layer. A second conductive layer is then positioned adjacent to and electrically insulated from the first conductive layer, so the second conductive layer does not block light from the photovoltaic layer. Finally, at least one through silicon via is then fabricated between the first node of the photovoltaic layer through the photovoltaic layer and the first conductive layer to the second conductive layer while at least one through silicon via is electrically insulated from the photovoltaic layer and the first conductive layer.
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the technology of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
For a more complete understanding of the present disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings.
In some embodiments, at least one via, such as a through silicon via (TSV), is electrically coupled to the second conductive layer 304 and the light receiving top node 302a, so electricity generated by the photovoltaic layer 302 travels through the body of the photovoltaic layer 302 to the second conductive layer 304. The through silicon vias 306 and 308 can have a sloped profile (e.g., as a result of a wet etch process). The through silicon vias 306 and 308 can be any conductive material, such as a metal or a silicon material, that conducts electricity through the photovoltaic cell 300. Each of the through silicon vias 306 and 308 respectively have first ends 306a, 308a electrically coupled to the light receiving top node 302a. Because the footprint of the first ends 306a and 308a are substantially smaller than the metal layer 108 as shown in
A light refracting layer 314 is positioned on the light receiving top node 302a to deflect light into the photovoltaic layer 302, and reduce the amount of light reflected (e.g., photon 316b). In another embodiment, the light refracting layer 314 is electrically coupled to the light receiving top node 302a. The light refracting layer 314 having translucent properties can deflect light photons (e.g., photon 316a) into the photovoltaic layer 302 and electrically conduct the generated electricity from the photovoltaic layer 302 to the through silicon via array 400 as to be described below in
The through silicon via connections to the light refracting layer 314 reduce or eliminate the need of having metallization requirements exist above the photovoltaic layer 302 because the through silicon vias can provide passage to the second conductive layer 304 through the body of the photovoltaic layer 302. For example, instead of having metal traces positioned on top of the photovoltaic cell 300 as shown in
Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the technology of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
