Abstract:
An organic light emitting diode (OLED) display comprises a substrate, an organic light emitting diode element having an organic light emitting layer disposed on the substrate. A conductive layer is disposed on the organic light emitting layer to serve as a common electrode for the OLED element. A photovoltaic cell disposed on the organic light emitting diode element, converting incident light into electricity, wherein the conductive layer serves as the common electrode for the photovoltaic cell.

Description:
BACKGROUND  
       [0001]     The invention relates to electroluminescent displays, and more particularly, to organic light emitting diode displays integrating photovoltaic cells.  
         [0002]     Among flat panel displays, organic light emitting diode (OLED) displays exhibit characteristics of self-emission, high brightness, wide viewing angle, high response, simple fabrication process, low power consumption, and good outdoor reliability, and are therefore widely applied in portable computers, notebooks, mobile phones, and personal digital assistances (PDAs).  
         [0003]     Organic light emitting diode displays exhibit self-emission with high brightness and therefore have different applications than conventional liquid crystal displays. By adopting different organic light emitting materials, full color organic light emitting diode displays can be achieved. Moreover, biasing low driving voltage, the organic light emitting diode display can be still visible at a high incline viewing angle.  
         [0004]     Conventional organic light emitting diode displays comprise a multi-layered structure with at least one light emitting layer sandwiched between an anode and a cathode. When a bias is applied between the anode and the-cathode, electrons and holes are separately generated and then recombined at the light emitting layer, thereby generating light.  
         [0005]     Conversely, solar energy converters such as photovoltaic cells convert environmental incident light into electricity. More specifically, as power consumption requirements become stricter, electronic devices require the integration of OLED devices and photovoltaic cell devices to deduce dependency upon a main power source.  
         [0006]     To improve power consumption efficiency, Japanese Laid-Open Patent Application No. 2002-006769, the entirety of which is hereby incorporated by reference, discloses an organic light emitting diode display.  FIG. 1  is a cross section of a conventional electronic device integrating a photovoltaic cell. An electronic device  100  comprises an organic light emitting diode device and a photovoltaic cell. The organic light emitting diode device is formed on a substrate  10 . For example, a plurality of organic light emitting diode elements  20  is formed on a substrate  10 . Each organic light emitting diode element  20  comprises a light emitting layer  24  interposed between a anode  22  and a cathode  26 . A frame  30  passivates the organic light emitting diode device. A plurality of photovoltaic cell device  
         [0007]     Considering the thickness of the conventional touch control panel integrated with an OLED display, touch control panel  14 , OLED display  52 , and the two substrates  50  and  12  and the gap  72  therebetween are space consumptive. Moreover, separately forming the touch control panel  14  and the OLED display  52  also incurs high production costs.  
       SUMMARY  
       [0008]     Accordingly, the invention provides a touch control panel integrated with an organic light emitting diode (OLED) display, capable of reducing the total thickness of electronic devices.  
         [0009]     The invention further provides an organic light emitting diode (OLED) display, comprising an organic light emitting diode (OLED) element having an organic light emitting layer. A conductive layer is disposed on the organic light emitting layer to serve as a common electrode for the OLED element. A photovoltaic cell element is disposed on the OLED element, converting incident light into electricity to drive the OLED element, wherein- the conductive layer serves as the common electrode for the photovoltaic cell.  
         [0010]     The invention further provides an organic light emitting diode (OLED) display, comprising a substrate. An organic light emitting diode (OLED) element having an organic light emitting layer is disposed on the substrate. A conductive layer is disposed on the organic light emitting layer to serve as a common electrode for the OLED element. A photovoltaic cell element is disposed on the OLED element, converting incident light into electricity to drive the OLED element, wherein the conductive layer serves as the common electrode for the photovoltaic cell.  
         [0011]     The invention further provides an organic light emitting diode (OLED) display comprising a substrate. A photovoltaic cell having a charge generation layer is disposed on the substrate. A conductive layer is disposed on the charge generation layer to serve as a common electrode for the photovoltaic cell. An organic light emitting diode (OLED) element is disposed on the photovoltaic cell. The photovoltaic cell converts incident light into electricity to drive the OLED element. The conductive layer serves as the common electrode for the OLED element. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein  
         [0013]      FIG. 1  is a cross section of a conventional electronic device integrating a photovoltaic cell;  
         [0014]      FIG. 2  is a cross section of an embodiment of an OLED display device integrating a photovoltaic cell; and  
         [0015]      FIG. 3  is a cross section of another embodiment of an OLED display device  300  integrating a photovoltaic cell. 
     
    
     DETAILED DESCRIPTION  
       [0016]      FIG. 2  is a cross section of an embodiment of an OLED display device  200  integrating a photovoltaic cell. Referring to  FIG. 2 , an OLED display device  200  comprises a substrate  210  with an OLED element  220  thereon. A photovoltaic cell  240  is disposed on the OLED element  220 . The photovoltaic cell  240  can convert incident light hv into electricity to drive the OLED element  220 . The OLED element  220  and the photovoltaic cell  240  share a common electrode  230 .  
         [0017]     The substrate  210  is a transparent substrate, such as a glass substrate or an active matrix substrate with a thin film transistor (TFT) array thereon.  
         [0018]     The OLED element  220  may preferably comprise a bottom emission OLED element. More specifically, the OLED element  220  emits light toward the substrate  210  or in the direction of an observer (arrow v). The OLED element  220  may comprise a first electrode  212  such as a transparent electrode disposed on the substrate  210 . The first electrode  212  comprises indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), or zinc oxide deposited by sputtering, electron beam (e-beam) evaporation, thermal evaporation, chemical vapor deposition (CVD), or thermal spray decomposition.  
         [0019]     An organic light emitting diode structure comprises a first hole transport layer  222  disposed on the first electrode  212 . An organic light emitting layer  224  is disposed on the first hole transport layer  222 . A first electron transport layer  226  is disposed on the organic light emitting layer  224 . The first hole transport layer  222 , organic light emitting layer  224 , and first electron transport layer  226  comprise the OLED element  220 . The organic light emitting layer  224  can be oligomer or polymer with single or multiple layers. The oligomer light emitting layer can be formed by thermal evaporation. Alternatively, the polymer light emitting layer can be formed by spin-on deposition, ink jet printing, or screen printing.  
         [0020]     A second electrode  230  serving as a common electrode between the OLED element  220  and the photovoltaic cell  240  is disposed on the first electron transport layer  226 . The second electrode  230  is an opaque electrode blocking light from the photovoltaic cell  240  into the OLED element  220 . The second electrode  230  may comprise calcium (Ca), silver (Ag), magnesium (Mg), aluminum (Al), lithium (Li), or other low work function materials, or combinations thereof, formed by vacuum thermal evaporation or sputtering.  
         [0021]     A photovoltaic cell  240  comprises an inorganic cell element or an organic cell element. According to an embodiment of the invention, the photovoltaic cell  240  can directly convert light into electricity by photovoltaic effect at a pn junction. Alternatively, the photovoltaic cell  240  can convert light into chemical energy, and then convert chemical energy into electricity.  
         [0022]     The photovoltaic cell  240  preferably comprises an organic photovoltaic cell. The fabrication process of the organic photovoltaic cell  240  is compatible with the fabrication process of the OLED element  220 . The photovoltaic cell  240  comprises a second electron transport layer  242  on the second electrode  230 . A charge generation layer  244  is disposed on the second electron transport layer  242 . A second hole transport layer  246  is disposed on the charge generation layer  244 . When incident light is transmitted into the charge generation layer  244 , electrons and holes are separately generated and transported into the second electron transport layer  242  and the second hole transport layer  246 . A third electrode  250  such as a transparent electrode is disposed on the second hole transport layer  246 . The third electrode  250  comprises indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), or zinc oxide deposited by sputtering, electron beam (e-beam) evaporation, thermal evaporation, chemical vapor deposition (CVD), or thermal spray decomposition.  
         [0023]     The third electrode  250  connects to the first electrode  212  through an external circuit  260 , comprising a capacitor  265 .  
         [0024]     In some embodiments of the invention, the first electrode can be a first cathode. The second electrode  230  can be a common anode. The third electrode  250  can be a second cathode. Alternatively, the first electrode  212  can be a first anode. The second electrode  230  can be a common cathode. The third electrode  250  can be a second anode.  
         [0025]      FIG. 3  is a cross section of another embodiment of an OLED display device  300  integrating a photovoltaic cell. Referring to  FIG. 3 , an OLED display device  300  comprises a substrate  310 . A photovoltaic cell  340  is disposed on the substrate  310 . An OLED element  320  is disposed on the photovoltaic cell  340 . The photovoltaic cell  340  can convert incident light hv into electricity to drive the OLED element  320 . The OLED element  320  and the photovoltaic cell  340  share a common electrode  330 .  
         [0026]     The substrate  310  is a transparent substrate, such as a glass substrate or an active matrix substrate with a thin film transistor (TFT) array thereon.  
         [0027]     The photovoltaic cell  340  comprises an inorganic cell element or an organic cell element. In some embodiments of the invention, the photovoltaic cell  340  can directly convert light into electricity by photovoltaic effect at a pn junction. Alternatively, the photovoltaic cell  240  can convert light into chemical energy, and then convert chemical energy into electricity.  
         [0028]     The photovoltaic cell  340  may preferably comprise an organic photovoltaic cell. The fabrication process of the organic photovoltaic cell  340  is compatible with the fabrication process of the OLED element  320 . The photovoltaic cell  340  comprises a first electrode  312  such as a transparent electrode disposed on the substrate  310 . The first electrode  312  comprises indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), or zinc oxide deposited by sputtering, electron beam (e-beam) evaporation, thermal evaporation, chemical vapor deposition (CVD), or thermal spray decomposition. A second electron transport layer  342  is disposed on the first electrode  312 . A charge generation layer  344  is disposed on the second electron transport layer  342 . A second hole transport layer  346  is disposed on the charge generation layer  344 . When incident light is transmitted into the charge generation layer  344 , electrons and holes are separately generated and transported into the second electron transport layer  342  and the second hole transport layer  346 .  
         [0029]     A second electrode  330  is disposed on the electron transport layer  324  acting as a common electrode between the OLED element  320  and the photovoltaic cell  340 . The second electrode  330  is an opaque electrode blocking light from the photovoltaic cell  340  into the OLED element  320 . The second electrode  330  may comprise calcium (Ca), silver (Ag), magnesium (Mg), aluminum (Al), lithium (Li), or other low work function materials, or combinations thereof, formed by vacuum thermal evaporation or sputtering.  
         [0030]     The organic light emitting diode element  320  may preferably comprise a top emission OLED element. More specifically, the OLED element  320  emits light toward the direction of an observer (arrow v). The OLED element  320  comprises a first hole transport layer  322  disposed on the second electrode  330 . An organic light emitting layer  324  is disposed on the first hole transport layer  322 . An electron transport layer  326  is disposed on the organic light emitting layer  322 . The first hole transport layer  322 , organic light emitting layer  324 , and first electron transport layer  326  comprise the organic light emitting diode element  320 . The organic light emitting layer  324  can be oligomer or polymer with single or multiple layers. The oligomer light emitting layer can be formed by thermal evaporation. Alternatively, the polymer light emitting layer  324  can be formed by spin-on deposition, ink jet printing, or screen printing.  
         [0031]     A third electrode  350  such as a transparent electrode is disposed on the first electron transport layer  326 . The third electrode  350  comprises indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), or zinc oxide deposited by sputtering, electron beam (e-beam) evaporation, thermal evaporation, chemical vapor deposition (CVD), or thermal spray decomposition.  
         [0032]     The third electrode  350  connects to the first electrode  312  through an external circuit  360 , comprising a capacitor  365 .  
         [0033]     The first electrode can be a first cathode. The second electrode  330  can be a common anode. The third electrode  350  can be a second cathode. Alternatively, the first electrode  312  can be a first anode. The second electrode  330  can be a common cathode. The third electrode  350  can be a second anode.  
         [0034]     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.