Patent Publication Number: US-2007102035-A1

Title: Method and Structure for Integrated Solar Cell LCD Panel

Description:
This application claims priority to provisional application Ser. No. 60/732,388; filed on Oct. 31, 2006; commonly assigned, and of which is hereby incorporated by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION  
      Portable electronics devices such as cell phones become indispensable part of daily life. As more features such as music and video added to cell phones, power consumption increases significantly. Battery life becomes a bottleneck. Furthermore, dead batteries in cell phones cause inconvenience and have safety concerns in an emergency situation. Commercially available stand-alone solar panel for charging portable electronic devices is bulky and cumbersome; therefore it has not been adopted widely by consumers. Thus, there is a need in the art for methods and apparatus for fabricating an integrate solar cell devices on LCD panel for photovoltaic electricity generation for portable electronic devices.  
     SUMMARY OF THE INVENTION  
      According to the present invention, techniques for manufacturing objects are provided. More particularly, the invention provides a method and device for integrating solar cell on LCD panels for photovoltaic electricity generation for portable electronic devices.  
      A typical LCD panel is consisted with a front polarizer, a color filter, Liquid Crystal layer, a TFT layer, a rear polarizer, and a light source layer. The color filter typically has 30-50% ‘black matrix’ area that overlaps the data bus lines and TFTs on the TFT substrate and absorbs both the ambient light and backlight. According to one embodiment of the present invention, the black matrix on the color filter substrate is replaced by solar cells. In another embodiment of the present invention, the solar cell is fabricated on the TFT substrate overlapping data bus lines and TFTs regions. Yet in another embodiment of the present invention, the solar cell is fabricated on a separated substrate and is placed on top of the polarizer and absorbs unpolarized ambient light.  
      According to a specific embodiment of the present invention, a lens array substrate is coupled between the light source layer and the TFT substrate. A micro lens collects the backlight within a pixel cell and focuses the light with the focal point or the beam waist at the solar cell layer. As a result, a larger solar cell area is applied to absorb more ambient light while maintaining high fill ratio of the LCD pixels.  
      According to another specific embodiment of the present invention, the solar cell material is selected from at least silicon, a single crystal silicon, poly-crystalline silicon, amorphous silicon, gallium arsenide, cadmium telluride, copper indium diselenide, organic/inorganic, or hybrid cells. The substrate material is selected from glass, metal, plastic or polymer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a simplified cross section diagram illustrating components of integrated solar cell on color filter of a LCD panel according to one embodiment of the present invention.  
       FIG. 2  is a simplified cross section diagram illustrating components of integrated solar cell on TFT substrate of a LCD panel according to one embodiment of the present invention.  
       FIG. 3  is a simplified cross section diagram illustrating components of integrated solar cell panel on top of polarizer panel of a LCD panel according to one embodiment of the present invention.  
       FIG. 4  is a simplified cross section diagram illustrating components of integrated solar cell LCD panel with micro lens according to one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      According to the present invention, techniques for manufacturing objects are provided. More particularly, the invention provides a method and device for fabricating an out-of-plane compliant micro actuator. The method and device can be applied to LCD panels as well as other devices, for example, sensors, detectors, and optical systems.  
      As illustrated in Prior Art diagrams, a conventional LCD panel has a black matrix on the color filter substrate covers data bus-line and TFT (not shown) regions and blocks both ambient light and backlight from reflecting back to outside. As a result, aperture ratio ranges from 50% to 70% for typical LCD panels. The remaining 30% to 50% panel area is covered by the black matrix.  
       FIG. 1  is a simplified cross section diagram illustrating components of integrated solar cell LCD panel according to one embodiment of the present invention. As illustrated, the black matrix on the color filter substrate  101  is replaced by solar cells  103 . The solar cell covers the data bus line  104  on a TFT substrate  102 . As depicted in A-A zoomed-in view, the solar cell is consisted with a p-n junction  105 , an AR coating, front contact  109  and back contact  111 . The solar cell absorbs light from both the ambient light  113  and backlight  115 . The absorbed light is converted into electricity that charges a battery.  
      In one embodiment of the present invention, the solar cell is fabricated directly on the color filter glass substrate using amorphous silicon and metallization similar to a TFT process. In another embodiment of the present invention, the solar cell is fabricated directly on the color filter glass substrate using polysilicon and metallization similar to a TFT process.  
       FIG. 2  is a simplified cross section diagram illustrating components of integrated solar cell LCD panel according to one embodiment of the present invention. As illustrated, solar cells  201  are fabricated on top as well as bottom of the data bus lines and TFTs (not shown). One fabrication method involves with using polysilicon and metallization similar to a TFT process. Dielectric layers  203  electrically isolates the solar cells from the data bus lines and TFTs. Similarly, a clear window region  205  is patterned on the color filter substrate above the solar cells, to allow maximum ambient light shedding on the top solar cells. The bottom solar cells absorb the backlight  115 .  
       FIG. 3  is a simplified cross section diagram illustrating components of integrated solar cell LCD panel according to one embodiment of the present invention. As illustrated, solar cells  301  are fabricated on a separated substrate  303 . The solar cell substrate is placed on top of the polarizer  305  and absorbs unpolarized ambient light  307 . The solar cells on the solar cell substrate are patterned to match the black matrix region on the color filter substrate  309 . The two substrates are aligned to each other  311 .  
      According to one embodiment of the present invention, the solar cell is fabricated directly on the glass substrate using amorphous or polycrystalline silicon and metallization similar to a TFT process. In another specific embodiment of the present invention, thin film solar cells such as CIGS (a compound of Copper, Indium, Gallium and Selenium), CIS (a compound of Copper Indium Diselenide) are fabricated on substrate materials such as glass, plastic or polymer.  
       FIG. 4  is a simplified cross section diagram illustrating components of integrated solar cell LCD panel with micro lens according to one embodiment of the present invention. As illustrated, a lens array substrate  401  is placed between the TFT substrate  403 . A micro lens  405  collects the backlight  407  within a pixel cell and focuses the light with the focal point or the beam waist  409  at the solar cell layer. As a result, a larger solar cell  411  can be placed to absorb more ambient light  413  without sacrificing the fill ratio of the LCD pixels.  
      It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.