Abstract:
A vertical organic light emitting transistor assembly and-a horizontal organic light emitting transistor assembly are provided. The vertical organic light emitting transistor assembly comprises a first/second vertical transistor and a first/second organic light emitting diode perpendicularly integrated with the first/second vertical transistor, respectively. The horizontal organic light emitting transistor assembly comprises a substrate, a third vertical transistor and a third organic light emitting diode. The third vertical transistor and the third organic light emitting diode are arranged abreast on the substrate. By integrating the organic light emitting diode and the vertical transistor into a unitary electronic element, the vertical transistor can efficiently drive the organic light emitting diode so that the organic light emitting transistor assembly can overcome limitations caused by existing manufacturing processes and adapt to extensive applications.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a vertical organic light emitting transistor assembly and a horizontal organic light emitting transistor assembly. More particularly, the present invention relates a vertical organic light emitting transistor assembly and a horizontal organic light emitting transistor assembly wherein vertical transistors and organic light emitting diodes are integrated. 
         [0003]    2. Description of Related Art 
         [0004]    Flexible electronic elements are electronic elements of the next generation and have manifold advantages such as light weight, compact size, ergonomic design adaption, flexibility and so on. These advantages, especially the flexibility that allows the elements to be freely bent or rolled, permit the flexible electronic elements of more extensive applications, such as flexible logics and memories, flexible sensors, flexible lighting, flexible energy and flexible display devices. In the known flexible electronic elements, the most fundamental one, as generally acknowledged, would be an organic transistor. 
         [0005]    According to U.S. Pat. No. 7,126,153, a prior organic transistor is capable of emitting light at high luminescence efficiency, operating at high speed, handling large electric power, and can be manufactured at low cost. The organic transistor includes an organic semiconductor layer as a light emission layer, arranged between a source electrode and a drain electrode. It also has gate electrodes provided at intervals approximately in the central part of the organic semiconductor layer, and approximately parallel to the source electrode and the drain electrode, wherein the gate electrodes are shaped like a comb or a mesh. However, while such prior gate electrode requires quite complex manufacturing processes, it would be a challenge to define gate borders. Consequently, any error in the manufacturing processes or gate border definition can adversely affect the luminescence efficiency of the organic transistors. 
         [0006]    Hence, it is necessary to overcome limitations caused by the existing manufacturing processes and simplify the manufacturing processes of organic transistors so as to allow the organic transistors to have both the benefits of the existing organic light emitting diode and the existing organic transistors in the attempt to extensively adapt the organic transistors to flexible display devices, flexible sensors, amplification circuits, driving circuits and so on. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a vertical organic light emitting transistor assembly and a horizontal organic light emitting transistor assembly. By integrating vertical transistors and organic light emitting diodes as a unitary electronic element, the vertical transistors can directly drive the organic light emitting diodes so as to downsize the organic light emitting transistor assembly. Hence, the applicability of the organic light emitting transistor assembly in various electronic devices can be expanded. 
         [0008]    To achieve this end, the present invention proposes a vertical organic light emitting transistor assembly that comprises a first vertical transistor, having a first electrode, a first organic layer stacked on the first electrode, and a second electrode located in the first organic layer; and a first organic light emitting diode, having a second organic layer perpendicularly stacked on the first vertical transistor; and a third electrode stacked on second organic layer. 
         [0009]    To achieve this end, the present invention further proposes a vertical organic light emitting transistor assembly that comprises a second vertical transistor, having a fifth electrode, a third organic layer stacked on the fifth electrode, an insulation layer stacked on the third organic layer; and a sixth electrode stacked on the insulation layer; and a second organic light emitting diode, having a fourth organic layer perpendicularly stacked on the second vertical transistor; and a seventh electrode stacked on the fourth organic layer. 
         [0010]    To achieve this end, the present invention further proposes a horizontal organic light emitting transistor assembly that comprises a substrate, a third vertical transistor arranged at a first location on the substrate and having a first collector, a first grid/base and a first emitter; and a third organic light emitting diode arranged at a second location on the substrate and having an anode an a cathode, wherein the anode is electrically connected to the first collector through a third conductor. 
         [0011]    By implementing the present invention, at least the following progressive effects are achievable: 
         [0012]    1. Downsizing the organic light emitting transistor assembly for facilitating its application to various electronic devices, 
         [0013]    2. Simplifying the manufacturing processes of the organic light emitting transistor, and 
         [0014]    3. Vertical transistors can drive organic light emitting diodes directly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0016]      FIG. 1  is a sectional drawing showing a first aspect of a vertical organic light emitting transistor assembly according to the present invention; 
           [0017]      FIG. 2  is a sectional drawing showing a second aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0018]      FIG. 3  is a sectional drawing showing a third aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0019]      FIG. 4  is a sectional drawing showing a fourth aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0020]      FIG. 5  is a sectional drawing showing a fifth aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0021]      FIG. 6  is a sectional drawing showing a sixth aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0022]      FIG. 7  is a sectional drawing showing a seventh aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0023]      FIG. 8  is a sectional drawing showing an eighth aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0024]      FIG. 9  is a sectional drawing showing a ninth aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0025]      FIG. 10  is a sectional drawing showing a tenth aspect of the vertical organic light emitting transistor assembly according to the present invention; 
           [0026]      FIG. 11  is a sectional drawing showing a first aspect of a horizontal organic light emitting transistor assembly according to the present invention; 
           [0027]      FIG. 12  is a sectional drawing showing a second aspect of the horizontal organic light emitting transistor assembly according to the present invention; 
           [0028]      FIG. 13  is a sectional drawing showing a third aspect of the horizontal organic light emitting transistor assembly according to the present invention; 
           [0029]      FIG. 14  is a sectional drawing showing a fourth aspect of the horizontal organic light emitting transistor assembly according to the present invention; 
           [0030]      FIG. 15  is a sectional drawing showing a fifth aspect of the horizontal organic light emitting transistor assembly according to the present invention; 
           [0031]      FIG. 16A  is a diagram showing a relationship between a third electrode voltage and a third electrode current of the vertical organic light emitting transistor assembly of  FIG. 3  at various second electrode voltages, wherein the second electrode has openings each being sized as 0.1 micron in diameter; 
           [0032]      FIG. 16B  is a diagram according to  FIG. 16A  showing a relationship between the second electrode voltage and an illumination when the third electrode voltage is −12V; 
           [0033]      FIG. 17A  is a diagram showing a relationship between the third electrode voltage and the third electrode current of the vertical organic light emitting transistor assembly of  FIG. 3  at various second electrode voltages, wherein the second electrode has openings each being sized as 0.2 micron in diameter; and 
           [0034]      FIG. 17B  is a diagram according to  FIG. 17A  showing a relationship between the second electrode voltage and the illumination when the third electrode voltage is −12V. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     First Preferred Embodiment of Vertical Organic Light Emitting Transistor Assembly 
       [0035]      FIGS. 1 through 5  illustrate a first, a second, a third, a fourth, and a fifth aspects of a vertical organic light emitting transistor assembly  10  according to the present invention. 
         [0036]    As can be seen in  FIG. 1 , in a first aspect of a vertical organic light emitting transistor according to the present invention, the vertical organic light emitting transistor assembly  10  comprises a first vertical transistor  11  and a first organic light emitting diode  12 . 
         [0037]    The first vertical transistor  11  has a first electrode  111 , a first organic layer  112 , and a second electrode  113 . The first organic layer  112  is stacked on the first electrode  111 , and the second electrode  113  is located in any portion of the first organic layer  112 , including being arranged on the first organic layer  112 . The second electrode  113  serves to control an amount of electron holes/electrons passing therethrough so as to modulate a luminance of the first organic light emitting diode  12 . The first organic layer  112  may be selected from a group consisting of an HIL (Hole Injection Layer), an HTL (Hole Transport Layer), an HBL (Hole Blocking Layer), an EBL (Electron Blocking Layer), an ETL (Electron Transport Layer) and an EIL (Electron Injection Layer). 
         [0038]    The first organic light emitting diode  12  has a second organic layer  121  and a third electrode  122 . The second organic layer  121  includes an EML (EMission Layer) and may further include at least one of an HIL (Hole Injection Layer), an HTL (Hole Transport Layer), an HBL (Hole Blocking Layer), an EBL (Electron Blocking Layer), an ETL (Electron Transport Layer) and an EIL (Electron Injection Layer) so as to reduce energy barrier difference between the layers and in turn enhance luminescence efficiency of the first organic light emitting diode  12 . The second organic layer  121  is perpendicularly stacked on the first vertical transistor  11 , for example, on the first organic layer  112  or the second electrode  113 , while the third electrode  122  is stacked on the second organic layer  121 . 
         [0039]    For instance, the first electrode  111  of the first vertical transistor  11  may be an anode made of gold, platinum, aluminum/molybdenum oxide, aluminum/molybdenum oxide/PEDOT, or a combination thereof. Or, the first electrode  111  may be a transparent electrode such as ITO (Indium Tin Oxide). The first organic layer  112  may include an HIL and an HTL, wherein the HIL may be stacked on the first electrode  111 , and the HTL may be then stacked on the HIL. The second electrode  113  may be a grid located in any portion of the HTL, including being arranged on the HTL. The third electrode  122  of the first organic light emitting diode  12  may be a cathode, and may be made of calcium/aluminum, lithium fluoride/aluminum, cesium fluoride/aluminum, barium/aluminum or a combination thereof. 
         [0040]    The second electrode  113  serves to control an amount of electron holes entering the first organic light emitting diode  12 . The electron holes are allowed to pass the second electrode  113  and enter the first organic light emitting diode  12  by properly modulating voltages of the second electrode  113  and the third electrode  122 . After entering the first organic light emitting diode  12 , the electron holes are recombined with the electrons injected by the third electrode  122  at the second organic layer  121  and thereby the EML of the second organic layer  121  emits light. 
         [0041]    In a further example, the first electrode  111  of the first vertical transistor  11  may be a cathode. The first organic layer  112  may include an ETL that may be stacked on the first electrode  111 . The second electrode  113  may be a grid located in any portion of the ETL, including being arranged on the ETL. The third electrode  122  may be an anode and may be made of gold, platinum, molybdenum oxide/aluminum, PEDOT/molybdenum oxide/aluminum, or a combination thereof. Alternatively, the third electrode  122  may be a transparent electrode such as ITO (Indium Tin Oxide). 
         [0042]    The second electrode  113  serves to control an amount of electrons entering the first organic light emitting diode  12 . The electrons are allowed to pass the second electrode  113  and enter the first organic light emitting diode  12  by properly modulating the voltages of the second electrode  113  and the third electrode  122 . After entering the first organic light emitting diode  12 , the electrons are recombined with the electron holes injected from the third electrode  122  at the second organic layer  121  and thereby the EML of the second organic layer  121  emits light. 
         [0043]    As shown in  FIGS. 1 and 3 , a transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the first vertical transistor  11 . In other words, the first electrode  111  of the first vertical transistor  11  may be arranged on the transparent substrate  13 , namely the glass substrate or the plastic substrate or so on. 
         [0044]    When the first electrode  111  is an anode and the third electrode  122  is a cathode materialized by a very thin metal electrode, the light emitted from the EML of the second organic layer  121  can be emitted upward through the third electrode  122 . Besides, when the first electrode  111  is the transparent electrode, the light can also pass the first electrode  111  and be emitted downward through the transparent substrate  13 . Similarly, when the first electrode  111  is a cathode and the third electrode  122  is an anode, appropriate materials may be adopted to enable the vertical organic light emitting transistor assembly  10  to emit light in both up and down directions. 
         [0045]    Alternatively, as shown in  FIGS. 2 and 4 , the transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the first organic light emitting diode  12 . In other words, the third electrode  122  of the first organic light emitting diode  12  may be arranged on the transparent substrate  13 , namely the glass substrate or the plastic substrate or so on. When the third electrode  122  is the transparent electrode, the light emitted from the EML of the second organic layer  121  can be also emitted downward through the transparent substrate  13 , namely the glass substrate or the plastic substrate. The transparent substrate  13  may be made of a flexible material so that the vertical organic light emitting transistor assembly  10  can be applied to flexible electronic devices. 
         [0046]      FIGS. 3 and 4  provide the third and the fourth aspects of the vertical organic light emitting transistor assembly  10 . Therein, the vertical organic light emitting transistor assembly  10  may further comprise a fourth electrode  123  arranged between the first organic layer  112  of the first vertical transistor  11  and the second organic layer  121  of the first organic light emitting diode  12 . The fourth electrode  123  may be made of a metal, such as aluminum or silver. Or, the fourth electrode  123  may be formed as a multi-layer structure comprising a highly conductive macromolecular material such as PEDOT or metal and other materials. Such multi-layer structure may be made of aluminum/molybdenum oxide, aluminum/molybdenum oxide/PEDOT, gold/PEDOT and so on. 
         [0047]    For example, when the first electrode  111  of the first vertical transistor  11  is an anode while the second electrode  113  is a grid, and the third electrode  122  of the first organic light emitting diode  12  is a cathode, the fourth electrode  123  is properly an anode. Otherwise, when the first electrode  111  of the first vertical transistor  11  is a cathode and the second electrode  113  is a grid wile the third electrode  122  of the first organic light emitting diode  12  is an anode, the fourth electrode  123  is properly a cathode. 
         [0048]    As shown in  FIG. 5 , any of the above aspects of the vertical organic light emitting transistor assembly  10  may be further comprise a hot-carrier transistor  40 , which has an emitter  41 , a base  42  and a collector  43 . Such hot-carrier transistor  40  may be realized by a polymer hot-carrier transistor disclosed in Journal of Applied Physics, Vol. 87, p. 253508 published in 2005. 
         [0049]    The collector  43  of the hot-carrier transistor  40  may be electrically connected to the second electrode  113  of the first vertical transistor  11  through a first conductor  14 . Thus, the current applied on the base  42  can modulate the output current of the collector  43  of the hot-carrier transistor  40  and in turn modulate the second electrode  113  of the vertical organic light emitting transistor assembly  10  with respect to its voltage so as to achieve current amplification. In addition, the luminance of the vertical organic light emitting transistor assembly  10  can be controlled by modulating the current on the base  42  of the hot-carrier transistor  40 . 
       Second Preferred Embodiment of Vertical Organic Light Emitting Transistor Assembly 
       [0050]      FIGS. 6 through 10  illustrate a sixth, a seventh, an eighth, a ninth, and a tenth aspects of a vertical organic light emitting transistor assembly  20  according to the present invention. 
         [0051]    As shown in  FIG. 6 , according to the sixth aspect of the vertical organic light emitting transistor assembly  20 , the vertical organic light emitting transistor assembly  20  comprises a second vertical transistor  21  and a second organic light emitting diode  22 . 
         [0052]    The second vertical transistor  21  has a fifth electrode  211 , a third organic layer  212 , an insulation layer  213  and a sixth electrode  214 . The third organic layer  212  is stacked on the fifth electrode  211 , and the insulation layer  213  is stacked between the third organic layer  212  and the sixth electrode  214 . The third organic layer  212  may be selected from a group consisting of an HIL (Hole Injection Layer), an HTL (Hole Transport Layer), an HBL (Hole Blocking Layer), an EBL (Electron Blocking Layer), an ETL (Electron Transport Layer) and an EIL (Electron Injection Layer). 
         [0053]    The second organic light emitting diode  22  has a fourth organic layer  221 , and a seventh electrode  222 . The fourth organic layer  221  includes an EML (EMission Layer) and may further include at least one of an HIL, an HTL, an HBL, an EBL, an ETL and an EIL so as to reduce energy barrier difference between the layers and in turn enhance luminesence efficiency of the second organic light emitting diode  22 . The fourth organic layer  221  is perpendicularly stacked on the second vertical transistor  21 , for example, on the sixth electrode  214 , while the seventh electrode  222  is stacked on the fourth organic layer  221 . 
         [0054]    For instance, the fifth electrode  211  of the second vertical transistor  21  may be an anode, and may be made of gold, platinum, aluminum/molybdenum oxide, aluminum/molybdenum oxide/PEDOT, or a combination thereof or may be a transparent electrode such as ITO (Indium Tin Oxide). The third organic layer  212  may include an HIL and an HTL, wherein the HIL may be stacked on the fifth electrode  211 , and the HTL may be then stacked on the HIL. The insulation layer  213  may be firstly stacked on the HTL and the sixth electrode  214  may be then stacked on the insulation layer  213 . The sixth electrode  214  may be a base. The fourth organic layer  221  of the second organic light emitting diode  22  may include an EML. The seventh electrode  222  may be a cathode made of calcium/aluminum, lithium fluoride/aluminum, cesium fluoride/aluminum, barium/aluminum or a combination thereof. 
         [0055]    When the insulation layer  213  and the sixth electrode  214  are in proper thicknesses, the electron holes injected from the fifth electrode  211  are allowed to tunnel through the insulation layer  213  and then pass through the sixth electrode  214  ballistically. By controlling the current of the sixth electrode  214 , the electron holes can pass the sixth electrode  214  and get into the fourth organic layer  221  without collision and contribute to the base current. 
         [0056]    After passing through the sixth electrode  214  and reaching the fourth organic layer  221 , the electron holes are recombined with the electrons injected from the seventh electrode  222  at the fourth organic layer  221  and thereby the EML of the fourth organic layer  221  emits light. Consequently, a light-emitting intensity of the second organic light emitting diode  22  can be controlled by using a current of the sixth electrode  214  to modulate the amount the electron holes entering the second organic light emitting diode  22 . 
         [0057]    In a further example, the fifth electrode  211  of the second vertical transistor  21  may be a cathode. The third organic layer  212  may include an ETL that may be stacked on the fifth electrode  211 . The insulation layer  213  may be firstly stacked on the ETL and the sixth electrode  214  may be then stacked on the insulation layer  213 . The sixth electrode  214  may be a base. The fourth organic layer  221  of the second organic light emitting diode  22  may include an EML. The seventh electrode  222  may be an anode made of gold, platinum, molybdenum oxide/aluminum, PEDOT/molybdenum oxide/aluminum, or a combination thereof. Alternatively, the seventh electrode  222  may be a transparent electrode such as ITO (Indium Tin Oxide). 
         [0058]    Similarly, when the insulation layer  213  and the sixth electrode  214  are in proper thicknesses, the electrons injected from the fifth electrode  211  are allowed to tunnel through the insulation layer  213  and then pass through the sixth electrode  214  ballistically. By controlling the current of the sixth electrode  214 , the electron can pass the sixth electrode  214  and get into the fourth organic layer  221  without collision and contribute to the base current. After passing through the sixth electrode  214  and reaching the fourth organic layer  221 , the electrons are recombined with the electron holes injected from the seventh electrode  222  at the fourth organic layer  221  and thereby the EML of the fourth organic layer  221  emits light. Consequently, a light-emitting intensity of the second organic light emitting diode  22  can be controlled by using the current of the sixth electrode  214  to modulate the amount the electrons entering the second organic light emitting diode  22 . 
         [0059]    As shown in  FIGS. 6 ,  8  and  9 , a transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the second vertical transistor  21 . In other words, the fifth electrode  211  of the second vertical transistor  21  may be arranged on the transparent substrate  13 , namely the glass substrate or the plastic substrate or so on. 
         [0060]    When the fifth electrode  211  is an anode and the seventh electrode  222  is a cathode materialized by a very thin metal electrode, the light emitted from the EML of the fourth organic layer  221  can be emitted upward through the seventh electrode  222 . Besides, when the fifth electrode  211  is the transparent electrode, the light can also pass the fifth electrode  211  and be emitted downward through the transparent substrate  13 . Similarly, when the fifth electrode  211  is a cathode and the seventh electrode  222  is an anode, appropriate materials may be adopted to enable the vertical organic light emitting transistor assembly  20  to emit light in both up and down directions. 
         [0061]    Alternatively, as shown in  FIG. 7 , the transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the second organic light emitting diode  22 . In other words, the seventh electrode  222  of the second organic light emitting diode  22  may be arranged on the transparent substrate  13 , namely the glass substrate or the plastic substrate or so on. When the seventh electrode  222  is the transparent electrode, the light emitted from the EML of the fourth organic layer  221  can be also emitted downward through the transparent substrate  13 , namely the glass substrate or the plastic substrate. The transparent substrate  13  may be made of a flexible material so that the vertical organic light emitting transistor assembly  20  can be applied to flexible electronic devices. 
         [0062]      FIG. 8  provides the eighth aspect of the vertical organic light emitting transistor assembly  20 . Therein, the second vertical transistor  21  may further comprise a fifth organic layer  215 , which may be an ETL, an EBL, an HTL, or an HBL. Besides, the fifth organic layer  215  may be arranged between the sixth electrode  214  of the second vertical transistor  21  and the fourth organic layer  221  of the second organic light emitting diode  22 . 
         [0063]    Though, according to  FIG. 8 , a transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the second vertical transistor  21 , in another aspect, the transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the second organic light emitting diode  22  (not shown) so that the seventh electrode  222  of the second organic light emitting diode  22  is arranged on the transparent substrate  13 , namely the glass substrate or the plastic substrate or so on. In addition, the seventh electrode  222  may be materialized as a transparent electrode. Thus, the light emitted from the EML of the fourth organic layer  221  can pass downward through the seventh electrode  222  and the transparent substrate  13  successively, namely the glass substrate or the plastic substrate and be emitted downward. 
         [0064]    In  FIG. 9 , according to the ninth aspect of the vertical organic light emitting transistor assembly  20 , a fifth organic layer  215  and an eighth electrode  216  are further contained therein. 
         [0065]    The fifth organic layer  215  may be an ETL or an HTL, which is stacked on the sixth electrode  214 . The eighth electrode  216  is further stacked on the fifth organic layer  215  so that the fifth organic layer  215  is sandwiched between the sixth electrode  214  and the eighth electrode  216  while the fourth organic layer  221  is further stacked on the eighth electrode  216 . The eighth electrode  216  may be made of a metal, such as aluminum or silver or so on. Or, the eighth electrode  216  may be formed as a multi-layer structure comprising a highly conductive macromolecular material such as PEDOT or metal and other materials. Such multi-layer structure may be made of aluminum/molybdenum oxide, aluminum/molybdenum oxide/PEDOT, gold/PEDOT and so on. 
         [0066]    For example, when the fifth electrode  211  of the second vertical transistor  21  is an anode and the sixth electrode  214  is a base while the seventh electrode  222  is a cathode, the eighth electrode  216  is properly an anode. Otherwise, when the fifth electrode  211  of the second vertical transistor  21  is a cathode and the sixth electrode  214  is a base while the seventh electrode  222  is an anode, the eighth electrode  216  is properly a cathode. 
         [0067]    In  FIG. 9 , according to the ninth aspect of the vertical organic light emitting transistor assembly  20 , a transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the second vertical transistor  21 . However, in another aspect, the transparent substrate  13 , such as a glass substrate or a plastic substrate, may be provided beside the second organic light emitting diode  22  (not shown). In addition, the seventh electrode  222  may be materialized as a very thin transparent electrode. Thus, the light emitted from the EML of the fourth organic layer  221  can pass downward through the seventh electrode  222  and the transparent substrate  13  successively, namely the glass substrate or the plastic substrate and be emitted downward. 
         [0068]    As shown in  FIG. 10 , any of the aforementioned aspects of the vertical organic light emitting transistor assembly  20  may be further comprise a space-charge-limited transistor  50 , which has an emitter  51 , a grid  52  and a collector  53 . Such space-charge-limited transistor  50  may be realized by a polymer spaced-charge-limited transistor disclosed in Journal of Applied Physics, Vol. 88, p. 223510 published in 2006. 
         [0069]    The collector  53  of the space-charge-limited transistor  50  may be electrically connected to the sixth electrode  214  of the second vertical transistor  21  through a second conductor  23 . Thus, the current of the sixth electrode  214  of the second vertical transistor  21  can be controlled by modulating a voltage of the grid  52  of the space-charge-limited transistor  50 , and in turn the electrons/electron holes are allowed to pass the sixth electrode  214  and reach the fourth organic layer  221  so as to recombined with the electrons/electron holes injected from the seventh electrode  222  at the fourth organic layer  221  and thereby the EML of the fourth organic layer  221  emits light. Consequently, a light-emitting intensity of the second organic light emitting diode  22  can be controlled by modulating the voltage of the grid  52  of the space-charge-limited transistor  50 . 
       Preferred Embodiment of Horizontal Organic Light Emitting Transistor Assembly 
       [0070]      FIGS. 11 through 15  illustrate a first, a second, a third, a fourth, and a fifth aspects of a horizontal organic light emitting transistor assembly  30  according to the present invention. 
         [0071]    As can be seen in  FIG. 11 , in the first aspect of the horizontal organic light emitting transistor assembly  30  according to the present invention, the horizontal organic light emitting transistor assembly  30  comprises a substrate  31 , a third vertical transistor  32  and a third organic light emitting diode  33 . 
         [0072]    The substrate  31  may be a transparent substrate, a glass substrate, or a plastic substrate. The substrate  31  may set the third vertical transistor  32  and the third organic light emitting diode  33  arranged abreast thereon. Moreover, the substrate  31  may be made of a flexible material so that the horizontal organic light emitting transistor assembly  30  can be applied to flexible electronic devices. 
         [0073]    The third vertical transistor  32  is deposited at a first location on the substrate  31 , wherein the first location may be any location on the substrate  31 . The third vertical transistor  32  may be a space-charge-limited transistor, which has a first collector  321 , a first grid  322  and a first emitter  323 . Alternatively, the third vertical transistor  32  may be a hot-carrier transistor, which has a first collector  321 , a first base (not shown) and a first emitter  323 . The space-charge-limited transistor and the hot-carrier transistor implemented herein are similar to those described previously on the first and second preferred embodiment of the present invention. 
         [0074]    The third organic light emitting diode  33  is deposited at a second location on the substrate  31 , wherein the second location may border on the first location so that the third organic light emitting diode  33  and the third vertical transistor  32  stand side by side. The third organic light emitting diode  33  has an anode  331  and a cathode  332 , wherein the anode  331  is electrically connected to the first collector  321  of the third vertical transistor  32  through a third conductor  34 . 
         [0075]    Referring to  FIG. 11 , in the first aspect of the horizontal organic light emitting transistor assembly  30 , the third vertical transistor  32  is deposited at the first location on the substrate  31  while the third organic light emitting diode  33  is deposited at the second location. Meanwhile, the first emitter  323  of the third vertical transistor  32  is in close contact with the substrate  31  while the third conductor  34  is positioned between the anode  331  of the third organic light emitting diode  33  and the substrate  31 . 
         [0076]    Since the third vertical transistor  32  is electrically connected to the third organic light emitting diode  33  through the third conductor  34 , after the current output running upward to the first collector  321 , the current output from the first emitter  323  can proceed to the anode  331  of the third organic light emitting diode  33  through the third conductor  34  so as to conduct the third organic light emitting diode  33 . Consequently, a light-emitting intensity of the third organic light emitting diode  33  can be controlled by the third vertical transistor  32 . 
         [0077]    Referring to  FIG. 12 , in the second aspect of the horizontal organic light emitting transistor assembly  30 , the first emitter  323  of the third vertical transistor  32  is in close contact with the substrate  31  while the cathode  332  of the third organic light emitting diode  33  is also in close contact with the substrate  31 . Thereby, when the first emitter  323  of the third vertical transistor  32  and the anode  331  of the third organic light emitting diode  33  are electrically connected through the third conductor  34 , after running upward to the first collector  321 , a current output by the first emitter  323  can proceed to the anode  331  of the third organic light emitting diode  33  through the third conductor  34 , thereby conducting the third organic light emitting diode  33  and dominating a light-emitting intensity of the third organic light emitting diode  33 . 
         [0078]    As shown in  FIG. 13 , the third aspect of the horizontal organic light emitting transistor assembly  30  has the third conductor  34  positioned between the first collector  321  of the third vertical transistor  32  and the substrate  31  and also positioned between the anode  331  of the third organic light emitting diode  33  and the substrate  31 . Thereby, a current output by the first emitter  323  of the third vertical transistor  32  can run downward to the first collector  321 , and then proceed to the anode  331  of the third organic light emitting diode  33  through the third conductor  34 , thereby conducting the third organic light emitting diode  33  and dominating a light-emitting intensity of the third organic light emitting diode  33 . 
         [0079]    In the fourth aspect of the horizontal organic light emitting transistor assembly  30  as shown in  FIG. 14 , the third conductor  34  is positioned between the first collector  321  of the third vertical transistor  32  and the substrate  31  while electrically connecting the anode  331  of the third organic light emitting diode  33 , wherein the cathode  332  of the third organic light emitting diode  33  is in close contact with the substrate  31 . Thereby, when a current output by the first emitter  323  runs downward to the first collector  321 , the third conductor  34  can pass the same to the anode  331  of the third organic light emitting diode  33  so that the third vertical transistor  32  can control a light-emitting intensity of the third organic light emitting diode  33 . 
         [0080]    In  FIG. 15 , the fifth aspect of the horizontal organic light emitting transistor assembly  30  further comprises a fourth vertical transistor  60 , which may be a hot-carrier transistor having a second collector  61 , a second base  62  and a second emitter  63 . Alternatively, the fourth vertical transistor  60  may be a space-charge-limited transistor having second collector  61 , a second grid (not shown) and a second emitter  63 . 
         [0081]    The second collector  61  of the fourth vertical transistor  60  is electrically connected to the third vertical transistor  32  through a fourth conductor  35 . The third vertical transistor  32  may be also a space-charge-limited transistor or a hot-carrier transistor. Thus, the fourth conductor  35  can electrically connect the first grid  322  of the space-charge-limited transistor or the first base of the hot-carrier transistor. By using the fourth vertical transistor  60  to modulate the current of the third vertical transistor  32 , the light-emitting intensity of the third organic light emitting diode  33  can in turn get controlled. 
         [0082]    &lt;Application of Vertical Organic Light Emitting Transistor Assembly&gt; 
         [0083]      FIG. 16A  is a diagram showing a relationship between a third electrode voltage V C  and a third electrode current I C  of the vertical organic light emitting transistor assembly  10  of  FIG. 3  at various second electrode voltages V G , wherein the second electrode  113  has openings each being sized as 0.1 micron in diameter.  FIG. 16B  is a diagram according to  FIG. 16A  showing a relationship between the second electrode voltage V G  and an illumination when the third electrode voltage V C  is −12V.  FIG. 17A  is a diagram showing the relationship between the third electrode voltage V C  and the third electrode current I C  of the vertical organic light emitting transistor assembly  10  of  FIG. 3  at various second electrode voltages V G , wherein the second electrode  113  has openings each being sized as 0.2 micron in diameter.  FIG. 17B  is a diagram according to  FIG. 17A  showing the relationship between the second electrode voltage V G  and the illumination when the third electrode voltage V C  is −12 CV. 
         [0084]    For further explaining the efficiency of the vertical organic light emitting transistor assembly  10 , the following description is directed to the third aspect of the vertical organic light emitting transistor assembly  10  as shown in  FIG. 3 . 
         [0085]    Herein, the first electrode  111  may be made of ITO/PEDOT. The first organic layer  112  may be made of poly(3-hexylthiophene). The second organic layer  121  may be made of Superyellow manufactured by German Covion (now merged by American Merck). The third electrode  122  may be made of barium/silver. The fourth electrode  123  may be made of aluminum/molybdenum oxide/PEDOT. In addition, the third electrode  122  is thin enough to be pervious to light by having a barium part as thick as 10 nanometer and a silver part as thick as 15 nanometer. The fourth electrode  123  is opaque and has an aluminum part as thick as about 60 nanometer. Moreover, the transparent substrate  13  for carrying the first electrode  111  is a glass substrate. 
         [0086]    As shown in  16 A, the second electrode  113  has opening each being sized as 0.1 micron in diameter. When the first electrode voltage is 0V, the third electrode current I C  can be modulated by varying the second electrode voltage V G  and the third electrode voltage V C . It can be demonstrated from  FIG. 16A  that when the second electrode voltage V G  being modulated from −0.9V to 0.9V, and the third electrode voltage V C  is −12V, the third electrode current I C  presents relatively high absolute values while the same second electrode voltage V G  is 0.9V. 
         [0087]    Thus, we can fix the first electrode voltage at 0V and fix the third electrode voltage V C  at −12V to further measure the light-emitting intensity of the vertical organic light emitting transistor assembly  10  at various second electrode voltages V G . As can be seen in  FIG. 16B , when the second electrode voltage V G  is modulated to 0.9V from −0.9V, the light-emitting intensity of the vertical organic light emitting transistor assembly  10  correspondingly raises from 7.5 cd/m 2  to 501 cd/m 2 . 
         [0088]    Thus, the present invention can easily satisfy a normal application of LEDs to a display device where only about 150 cd/m 2  to 200 cd/m 2  of light-emitting intensity of the LED is required. Furthermore, by modulating the second electrode voltage V G  and third electrode voltage V C , a variable light-emitting intensity can be provided according to practical needs. Consequently, the vertical organic light emitting transistor assembly  10  is readily adaptive to a display device or any other electronic devices. 
         [0089]    On the other hand, the second electrode  113  having a different opening size may be also implemented. For example, the second electrode  113  may have openings each being sized as 0.2 micron in diameter.  FIG. 17A  is a diagram showing the relationship between the third electrode voltage V C  and the third electrode current I C  of the vertical organic light emitting transistor of  FIG. 3  at various second electrode voltages, wherein the second electrode  113  has openings each being sized as 0.2 micron. 
         [0090]    Through  FIG. 17A , with the same second electrode voltage V G , the same third electrode voltage V C  and the same third electrode current I C , the relative large size of the openings of the second electrode  113  leads to a absolute value greater than that in  FIG. 16A . Besides, as shown in  FIG. 17B , the present vertical organic light emitting transistor assembly  10  provides a light-emitting intensity greater than that of the former vertical organic light emitting transistor assembly  10  of  FIG. 16  B. As a conclusion, the opening size of the second electrode  113  can be implemented as a factor in modulating the light-emitting intensity of the vertical organic light emitting transistor assembly  10 . 
         [0091]    Although the particular embodiments of the invention have been described in detail for purposes of illustration, it will be understood by one of ordinary skill in the art that numerous variations will be possible to the disclosed embodiments without going outside the scope of the invention as disclosed in the claims.