Patent Publication Number: US-2023154927-A1

Title: Display device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation (CA) of U.S. Patent application for “Display device”, U.S. application Ser. No. 17/147,189 filed on Jan. 12, 2021; U.S. application Ser. No. 17/147,189 is a continuation (CA) of U.S. application Ser. No. 16/733,809 filed on Jan. 3, 2020; U.S. application Ser. No. 16/733,809 is a continuation (CA) of U.S. application Ser. No. 15/934,678 filed on Mar. 23, 2018; and the subject matter of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to a display device, and more particularly to a display device integrated with a light detecting element. 
     2. Description of Related Art 
     Nowadays, the display devices are required to have not only the display function but also other functions such as touch or identification functions. In addition, for a purpose that the display devices have ultra narrow border (higher display-to-body ratio), sensors have to be embedded into display region of the display devices. Hence, how to integrate a sensor into the display region without reducing the accuracy or the resolution but keep the display performance of the display device is an issue. 
     SUMMARY 
     The object of the present disclosure is to provide an electronic device integrated with a light detecting element. 
     One aspect of the present disclosure provides an electronic device which comprises: a substrate; a first metal layer, disposed on the substrate and having a first hole; a second metal layer, disposed on the substrate and having a second hole; a light detecting element for detecting a light passing through the first hole and the second hole; a transistor, disposed on the substrate; and a light shielding layer, disposed between the substrate and the transistor. 
     Another aspect of the present disclosure provides an electronic device which comprises: a substrate; a first metal layer, disposed on the substrate and having a first hole; a second metal layer, disposed on the substrate and having a second hole, wherein the first metal layer is disposed between the substrate and the second metal layer; and a light detecting element for detecting a light passing through the first hole and the second hole, wherein the first hole has a first width, the second hole has a second width, and the second width is different from the first width. 
     Other novel features of the disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross sectional view of a display device according to Embodiment 1 of the present disclosure. 
         FIG.  2 A  is a perspective view showing a region of a second metal layer close to a second pinhole. 
         FIG.  2 B  is a perspective view showing a region of a first metal layer close to a first pinhole. 
         FIG.  3    is a cross sectional view of a display device according to Embodiment 2 of the present disclosure. 
         FIG.  4    is a cross sectional view of a display device according to Embodiment 3 of the present disclosure. 
         FIG.  5    is a cross sectional view of a display device according to Embodiment 4 of the present disclosure. 
         FIG.  6    is a cross sectional view of a display device according to Embodiment 5 of the present disclosure. 
         FIG.  7    is a cross sectional view of a display device according to Embodiment 6 of the present disclosure. 
         FIG.  8    is a cross sectional view of a display device according to Embodiment 7 of the present disclosure. 
         FIG.  9    is a cross sectional view of a display device according to Embodiment 8 of the present disclosure. 
         FIG.  10    is a cross sectional view of a display device according to Embodiment 9 of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENT 
     The following embodiments when read with the accompanying drawings are made to clearly exhibit the above-mentioned and other technical contents, features and/or effects of the present disclosure. Through the exposition by means of the specific embodiments, people would further understand the technical means and effects the present disclosure adopts to achieve the above-indicated objectives. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present disclosure should be encompassed by the appended claims. 
     Furthermore, the ordinals recited in the specification and the claims such as “first”, “second” and so on are intended only to describe the elements claimed and imply or represent neither that the claimed elements have any proceeding ordinals, nor that sequence between one claimed element and another claimed element or between steps of a manufacturing method. The use of these ordinals is merely to differentiate one claimed element having a certain designation from another claimed element having the same designation. 
     Furthermore, the ordinals recited in the specification and the claims such as “above”, “over”, or “on” are intended not only directly contact with the other element, but also intended indirectly contact with the other element. Similarly, the ordinals recited in the specification and the claims such as “below”, or “under” are intended not only directly contact with the other element but also intended indirectly contact with the other element. 
     In addition, the features in different embodiments of the present disclosure can be mixed to form another embodiment. 
     Embodiment 1 
       FIG.  1    is a cross sectional view of a display device of the present embodiment. A substrate  11  is provided, which can be a quartz substrate, a glass substrate, a plastic substrate, a metal foil substrate, a composite substrate of plastic and metal, or other inflexible or flexible substrates. A light shielding layer  121  and a reflective layer  122  is disposed on the substrate  11 , and the light shielding layer  121  and the reflective layer  122  may respectively comprise metal (for example, Ag, Al, Ti, Cr, or Mo, but the present disclosure is not limited thereto) or alloy formed as a single layer structure or a multilayer structure by the same process in the embodiment. In other embodiment, at least one of the light shielding layer  121  and the reflective layer  122  may comprises black resin, or multi transparent insulation layers with different refraction indexes. A buffer layer  13  is disposed on the light shielding layer  121  and the reflective layer  122 , and the buffer layer  13  may comprise silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, resin, polymer, photoresist, or a combination thereof. 
     A first semiconductor portion  141  and a second semiconductor portion  142  are respectively disposed on the buffer layer  13 , and the first semiconductor portion  141  and the second semiconductor portion  142  may comprise amorphous silicon, low temperature poly-silicon, or Indium Gallium Zinc Oxide (IGZO). Next, a first gate insulating layer  151  is disposed on the first semiconductor portion  141  and the second semiconductor portion  142 , and the first gate insulating layer  151  may comprise silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, resin, polymer, photoresist, or a combination thereof. Then, a first metal layer  16  is disposed on the first gate insulating layer  151 , wherein the first metal layer  16  comprises a first gate electrode  161  corresponding to the first semiconductor portion  141  and a second gate electrode  162  corresponding to the second semiconductor portion  142 , and the first metal layer  16  further comprises a first pinhole  163 . The first pinhole  163  is an enclosed opening disposed within a pattern of the first metal layer  16 , and the pattern may be or may not be connected with the first gate electrode  161  or the second gate electrode  162 . A first insulating layer  171  is disposed on the first metal layer  16 . A second metal layer  18  is disposed on the first insulating layer  171 , wherein the second metal layer  18  comprises a first source electrode  181 , a first drain electrode  182 , a second source electrode  183  and a second drain electrode  184 , and the second metal layer  18  further comprises a second pinhole  185 . The second pinhole  185  is an enclosed opening disposed within a pattern of the second metal layer  18 , and the pattern may be or may not be connected with the first source electrode  181 , the first drain electrode  182 , the second source electrode  183 , or the second drain electrode  184 . Herein, the first metal layer  16  and the second metal layer  18  may comprise Cu, Al, Ti, Cr, Mo, an alloy thereof, or a combination thereof, or other electrode materials. The first insulating layer  171  may comprise silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, resin, polymer, photoresist, or a combination thereof, but the present disclosure is not limited thereto. Hence, a light detecting element S is formed, which comprises: the first semiconductor portion  141 ; the first gate electrode  161  corresponding to the first semiconductor portion  141 ; and the first source electrode  181  and the first drain electrode  182  respectively electrically connected to the first semiconductor portion  141 . In addition, a driving element TFT is also formed, which comprises: the second semiconductor portion  142 ; the second gate electrode  162  corresponding to the second semiconductor portion  142 ; and the second source electrode  183  and the second drain electrode  184  respectively electrically connected to the second semiconductor portion  142 . The driving element TFT may directly or indirectly electrically connected to the light detecting element S. 
     Herein, both the light detecting element S and the driving element TFT are transistors with a top gate structure; but the present disclosure is not limited thereto, and a transistor with a bottom gate structure may also be used as one of or both the light detecting element S and the driving element TFT. In addition, the driving element TFT used herein is an amorphous silicon transistor or a low-temperature poly-silicon (LTPS) transistor; but the present disclosure is not limited thereto, and an oxide semiconductor transistor (such as IGZO transistor) may also be used as the driving element TFT. Furthermore, the light detecting element S used herein is a transistor; but the present disclosure is not limited thereto, and other type of light detecting element (for example, a photodiode) can also be used as the light detecting element S, as long as the purpose of signal sensing can be achieved. 
     A passivation layer  19  is disposed on the second metal layer  18 , and the passivation layer  19  may comprise silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, resin, polymer, photoresist, or a combination thereof. A first pixel electrode layer  21  is disposed on the passivation layer  19  and electrically connected to the driving element TFT. A pixel defining layer  23  is disposed on the first pixel electrode layer  21  and has an opening to expose the first pixel electrode layer  21  to define a light emitting region E (a display unit). The pixel defining layer  23  may comprise silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, resin, polymer, photoresist, or a combination thereof, but the present disclosure is not limited thereto. A light emitting layer  22  is disposed in the opening of the pixel defining layer  23 , and a part of the light emitting layer  22  may be disposed between the pixel defining layer  23  and the first pixel electrode layer  21  or a part of the light emitting layer  22  may be disposed on the sidewall of the opening of the pixel defining layer  23 . The light emitting layer  22  may comprise organic light emitting material, inorganic light emitting material, or quantum dots material. A second pixel electrode layer  24  is disposed on the pixel defining layer  23  and in contact with the light emitting layer  22 . The light emitting layer  22  is disposed between the first pixel electrode layer  21  and the second pixel electrode layer  24 . Hence, the display device of the present disclosure is obtained, which is a self emitting type organic light emitting diode (OLED) display device. In other embodiment, the display device may be a self-emitting type inorganic light emitting diode (LED) display device, or a self-emitting type quantum dot light emitting diode (QLED) display device. Herein, the first pixel electrode layer  21  may comprise Ag, Al, Al, Ti, Cr, Mo, an alloy thereof, or a combination thereof, or other material with high reflective properties; and the second pixel electrode layer  24  may mainly comprise transparent conductive metal oxide such as ITO, IZO, ITZO, IGZO, or AZO. In some embodiments of the present disclosure, the second pixel electrode layer  24  may comprise Ag, Al, Al, Ti, Cr, Mo, an alloy thereof, or a combination thereof for reducing resistance, but not substantially interfering with the display performance of the display device. The second pixel electrode layer  24  is primarily transparent in the present disclosure. However, the present disclosure is not limited thereto. 
     As shown in  FIG.  1   , the display device of the present embodiment comprises: a substrate  11 ; a first metal layer  16 , disposed on the substrate  11  and having a first pinhole  163 ; a second metal layer  18 , disposed on the first metal layer  16  and having a second pinhole  185 ; a first pixel electrode layer  21 , disposed on the second metal layer  18 ; a second pixel electrode layer  24 , disposed on the first pixel electrode layer  21 ; and a light detecting element S for detecting a light passing through at least the second pinhole  185  and the first pinhole  163 . The light may pass through or may not pass through the first pixel electrode layer  21  or the second pixel electrode  24  depending on layout design. 
     Herein, the first pinhole  163  of the first metal layer  16  and the second pinhole  185  of the second metal layer  18  can create a light path. When providing an informative photo signal (for example, visible light, near IR or IR light signal), the provided photo signal can pass through the light path created by the first pinhole  163  and the second pinhole  185  and reach to the light detecting element S. Because the first pinhole  163  and the second pinhole  185  can guide light to the light detecting element S embedded in the display device, the accuracy or resolution of the light detecting element S can further be improved. In addition, because the light detecting element S is embedded into the display region of the display device, the display-to-body ratio can also be improved, and the border of the display device could be further reduced. 
     In the present embodiment, because the first pixel electrode layer  21  is a reflective electrode, the first pixel electrode layer  21  has a third pinhole  211 . Hence, the third pinhole  211  together with the first pinhole  163  and the second pinhole  185  create the light path, so the light can pass through the third pinhole  211 , the second pinhole  185  and the first pinhole  163  and can be detected by the light detecting element S. 
     In another embodiment of the present disclosure, the second pixel electrode layer  24  may selectively comprise a fourth pinhole (not shown in the figure), thus the fourth pinhole together with the first pinhole  163 , the second pinhole  185  and the third pinhole  211  create the light path. 
     However, in other embodiment of the present disclosure, if the display device is a bottom emission type, the first pixel electrode layer  21  can be a transparent electrode as illustrated before, and the first pixel electrode layer  21  does not have to comprise the third pinhole. 
     In the present embodiment, the first pinhole  163 , the second pinhole  185  and the third pinhole  211  are an enclosed hole, in which a sidewall of the enclosed hole is continuous. In addition, the first pinhole  163  has a first width W 1 , the second pinhole  185  has a second width W 2 , and the first width W 1  and the second width W 2  are different. The third pinhole  211  has a third width W 3 , and the third width W 3  is also different from the first width W 1  and the second width W 2 . Herein, the first width W 1 , the second width W 2  and the third width W 3  respectively refer to the average width (average of maximum width of a pinhole plus minimum width of the pinhole) or diameter of the first pinhole  163 , the second pinhole  185  and the third pinhole  211 . The relation between the first width W 1 , the second width W 2  and the third width W 3  are not particularly limited. In the present embodiment, the widths are gradually increased from the first width W 1 , the second width W 2  to the third width W 3  (W 1 &lt;W 2 &lt;W 3 ). In another embodiment of the present disclosure, the widths can be gradually reduced from the first width W 1 , the second width W 2  to the third width W 3  (W 1 &gt;W 2 &gt;W 3 ). In another embodiment of the present disclosure, the second width can be greater than the first width W 1  or the third width W 3  (W 2 &gt;W 1 , or W 2 &gt;W 3 ). In further another embodiment of the present disclosure, the widths of two or three of the first width W 1 , the second width W 2  and the third width W 3  can be the same (W 1 =W 2 ≠W 3 , W 2 =W 3 ≠W 1 , W 3 =W 1 ≠W 2 , or W 1 =W 2 =W 3 ). 
     In the present embodiment, the light detecting element S is formed by the first metal layer  16  and the second metal layer  18 . In detail, the first metal layer  16  comprises a first gate electrode  161 , the second metal layer  18  comprises a first source electrode  181  and a first drain electrode  182 , and the light detecting element S comprises the first gate electrode  161 , the first source electrode  181  and the first drain electrode  182 . 
     In the present embodiment, the light detecting element S is disposed on the substrate  11 , and the display device further comprises a reflective layer  122  disposed between the substrate  11  and the light detecting element S. Since the light is laterally injected into the display device and is not injected into the light detecting element S in a normal direction of the display device, the reflective layer  122  can reflect the light to the light detecting element S after the light passes through the third pinhole  211 , the second pinhole  185  and the first pinhole  163  to the reflective layer  122 . 
       FIG.  2 A  is an enlarged view of a region of a second metal layer close to a second pinhole shown in  FIG.  1   , and  FIG.  2 B  is an enlarged view of a region of a first metal layer close to a first pinhole shown in  FIG.  1   . In the present embodiment, a first edge  1631  of the first pinhole  163  has a first slope α, and a second edge  1851  of the second pinhole  185  has a second slope β. The first slope α is measured at 50% thickness of the first metal layer  16 , and the second slope β is measured at 50% thickness of the second metal layer  18 . In one embodiment of the present disclosure, the first slope α and the second slope β are different if the materials for the first metal layer  16  and the second metal layer  18  are different or the thickness of the first metal layer  16  and the second metal layer  18  are different. In another embodiment of the present disclosure, the first slope α and the second slope β are identical if the materials and the thicknesses for the first metal layer  16  and the second metal layer  18  are the same. Herein, the first slope α and the second slope β can respectively be less than 90°. 
     In the present embodiment, one light detecting element is disposed in and corresponding to one subpixel region. However, the present disclosure is not limited thereto. In another embodiment of the present disclosure, one light detecting element S is disposed in and corresponding to a region including plural subpixel regions. In addition, plural light detecting elements can be disposed in more than one part of the display region or in the whole display region of the display device, and the plural light detecting elements can be disposed randomly or evenly in the display region of the display device. 
     Embodiment 2 
       FIG.  3    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 1, except for the following. 
     In the present embodiment, the first pixel electrode layer  21  does not extend and overlap the first pinhole  163  and the second pinhole  185 , and the first pixel electrode layer  21  dose not comprises a third pinhole  211  (as shown in  FIG.  1   ). 
     Embodiment 3 
       FIG.  4    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 1, except for the following. 
     In the present embodiment, the light detecting element S is a transistor with a bottom gate structure. Herein, a doped semiconductor region  143  with improved conductivity is used as a gate electrode of the light detecting element S, the doped semiconductor region  143  may use the same material with the second semiconductor portion  142  but with additional impurity doped within it. The doped semiconductor region  143  and the second semiconductor portion  142  may comprise amorphous silicon, poly-silicon, or IGZO, but the present disclosure is not limited thereto. The gate electrode of the light detecting element S can be formed by metal (Cu, Al, Ti, Cr, Mo, an alloy thereof, or a combination thereof), transparent conductive metal oxide (ITO, IZO, ITZO, IGZO, or AZO), or other kind of doped semiconductor material (amorphous silicon, poly-silicon, or IGZO). After forming the first gate insulating layer  151  on the doped semiconductor region  143  and the second semiconductor portion  142 , a first semiconductor region  14 ′ formed by another semiconductor layer is disposed on the first gate insulating layer  151 . The first semiconductor region  14 ′ may comprise amorphous silicon, poly-silicon, or IGZO. A second gate insulating layer  152  is disposed on the first semiconductor region  14 ′, and the material for the second gate insulating layer  152  can be similar to that of the first gate insulating layer  151  and is not repeated again. The first metal layer comprising a second gate electrode  162 , a first source electrode  164  and a first drain electrode  165  are disposed on the second gate insulating layer  152  to obtain the light detecting element S. 
     Herein, the first metal layer comprises a first source electrode  164  and a first drain electrode  165 , the light detecting element comprises the first source electrode  164  and the first drain electrode  165 , and the first pinhole  163  is a space formed between the first source electrode  164  and the first drain electrode  165  in top view. 
     In addition, the first pinhole  163 , the second pinhole  185  and the third pinhole  211  are vertically aligned to form a light path, which means the first pinhole  163 , the second pinhole  185  and the third pinhole  211  overlaps the light detecting element S in a normal direction of the display device. Hence, the photo signal can directly reach to the light detecting element S and the display device of the present disclosure does not have to equip with the reflective layer  122 . 
     Embodiment 4 
       FIG.  5    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 3, except for the following. 
     In the present embodiment, a first electrode layer  31  is formed on the passivation layer  19  and electrically connected to the driving element TFT, an insulating layer  32  is formed on the first electrode layer  31 , and then a second electrode layer  33  is formed on the insulating layer  32 . Herein, the first electrode layer  31  and the second electrode layer  33  can respectively be a transparent electrode illustrated before. The material for the insulating layer  32  can be the same as that for the first insulating layer  171 , and is not repeated again. 
     The display device of the present disclosure is a liquid crystal display (LCD) device, not a self-emitting type of display, wherein the first electrode layer  31  is used as a common electrode, and the second electrode layer  33  is used as a pixel electrode. In another embodiment of the present disclosure, the first electrode layer  31  can be used as a pixel electrode and the second electrode layer  33  can be used as a common electrode if the first electrode layer  31  is electrically connected to the driving element TFT. 
     In the present embodiment, the first electrode layer  31  comprises a third pinhole  311 , and the first pinhole  163 , the second pinhole  185  and the third pinhole  211  are vertically aligned to form a light path. The first pinhole  163 , the second pinhole  185 , and the third pinhole  211  are overlapped in a normal direction of the display device. In another embodiment of the present disclosure, the first electrode layer  31  does not comprise the third pinhole since the first electrode layer  31  is a transparent electrode that the light is capable of passing through. 
     Embodiment 5 
       FIG.  6    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 4, except for the following. 
     In the present embodiment, the first metal layer comprises a first gate electrode  161  and a second gate electrode  162 , and the first insulating layer  171  is disposed on the first metal layer. A first semiconductor portion  141  is disposed on the first insulating layer  171  and corresponds to the first gate electrode  161 . A second insulating layer  172  is formed on the first semiconductor portion  141 . The material for the second insulating layer  172  is similar to that for the first insulating layer  171 , and is not repeated again. The second metal layer is disposed on the second insulating layer  172  and comprises a first source electrode  181 , a first drain electrode  182 , a second source electrode  183  and a second drain electrode  184 . 
     Hence, the display device of the present embodiment comprises: a substrate  11 ; a second metal layer (comprising the first source electrode  181  and the first drain electrode  182 ) disposed on the substrate  11  and having a second pinhole  185 ; a pixel electrode layer  31 , disposed on the second metal layer; and a light detecting element S for detecting a light passing through the second pinhole  185 . Herein, the light detecting element S comprises: the first gate electrode  161 ; the first semiconductor portion  141  corresponding to the first gate electrode  161 ; and the first source electrode  181  and the first drain electrode  182  electrically connects to the first semiconductor portion  141 . In addition, the second pinhole  185  is a space between the first source electrode  181  and the first drain electrode  182 . 
     Furthermore, in the present embodiment, the display device further comprises: a driving element TFT electrically connected to the pixel electrode layer  31 , wherein the light detecting element S comprises a first semiconductor portion  141 , the driving element TFT comprises a second semiconductor portion  142 , and a thickness Ti of the first semiconductor portion  141  and a thickness T 2  of the second semiconductor portion  142  are different. In the present embodiment, the thickness T 1  of the first semiconductor portion  141  is greater than the thickness T 2  of the second semiconductor portion  142 . In the present embodiment, the first semiconductor portion  141  may comprise amorphous silicon, and the second semiconductor portion  142  may comprise poly-silicon. When the thickness T 1  of the first semiconductor portion  141  is increased, the sensing resolution of the light detecting element S or the intensity of the photo signal received by the light detecting element S can be improved. In one embodiment of the present disclosure, the thickness T 1  of the first semiconductor portion  141  can be ranged from 500 nm to 800 nm. 
     Embodiment 6 
       FIG.  7    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 1, except that the light detecting element S is disposed under the substrate  11  (on the backside of the substrate  11 ) which means the light detecting element S is disposed on a side of the substrate  11  opposite to another side of the substrate  11  where the first meta layer  16  is formed thereon, and the display device does not comprise the reflective layer  122  (as shown in  FIG.  1   ) in the present embodiment. In the present embodiment, the light detecting element S is illustrated as one light detecting unit being disposed in (or corresponding to) one subpixel area, but this embodiment is not limited thereto. In other embodiment, one light detecting unit could be disposed in (or corresponding to) a plurality of subpixel areas. 
     Embodiment 7 
       FIG.  8    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 6, except for the following. 
     In Embodiment 6, the light is laterally injected into the display device to the light detecting element S disposed under the substrate  11 . In the present embodiment, the first pinhole  163 , the second pinhole  185  and the third pinhole  211  overlap the light detecting element S in a normal direction of the display device, so the light injects into the display device in a normal direction of the display device to the light detecting element S disposed under the substrate  11   
     Embodiment 8 
       FIG.  9    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 4, except for the following. 
     In the present embodiment, the first metal layer  16  comprises a first pinhole  163 , and the second metal layer  18  comprises a second pinhole  185 . In addition, the light detecting element S is disposed under the substrate  11  (on the backside of the substrate  11 ) in the present embodiment. 
     In the present embodiment, the light detecting element S, the first pinhole  163  and the second pinhole  185  should be as better as disposed outside of the light emitting region E for keeping the transparency. 
     Embodiment 9 
       FIG.  10    is a cross sectional view of a display device of the present embodiment. The display device of the present embodiment is similar to that of Embodiment 1, except for the following. 
     In the present embodiment, the first semiconductor portion  141  and the second semiconductor portion  142  are formed at different steps. After the second semiconductor portion  142  is disposed on the buffer layer  13 , the first gate insulating layer  151  is formed on the second semiconductor portion  142 . Then, the first semiconductor portion  141  is formed on the first gate insulating layer  151 , and another second gate insulating layer  152  is formed on the first semiconductor portion  141 . The material for the second gate insulating layer  152  is similar to that of first gate insulating layer  151 , and is not repeated again. 
     In the present embodiment, a thickness Ti of the first semiconductor portion  141  and a thickness T 2  of the second semiconductor portion  142  are different. Especially, the thickness T 1  of the first semiconductor portion  141  is greater than the thickness T 2  of the second semiconductor portion  142 . When the thickness Ti of the first semiconductor portion  141  is increased, the sensing resolution of the light detecting element S or the intensity of the photo signal received by the light detecting element S can be improved. 
     In the foregoing embodiments, the first semiconductor portion  141  may comprise a silicon-based material, and the crystallinity (crystallization ratio) of the silicon-based material ranged from amorphous silicon to poly-silicon, according to the desired detecting wavelength of the light detecting element S. The second semiconductor portion  142  may comprise silicon-based material with higher crystallinity (crystallization ratio) than the first semiconductor portion  141 . In the present embodiment, the first semiconductor portion  141  may comprise amorphous silicon, and the second semiconductor portion  142  may comprise poly-silicon, but the present disclosure is not limited thereto. In other embodiment, both the first semiconductor portion  141  and the second semiconductor portion  142  may comprise poly-silicon with different crystallinity. 
     In the aforesaid embodiments, the OLED display device and the LCD device are illustrated. However, the present disclosure is not limited thereto. The display medium used in the display device can be quantum dots (QDs), fluorescence molecules, phosphors, normal inorganic light-emitting diodes (normal LEDs, in which the size of the chip contained therein is ranged from 300 μm to 10 mm), mini inorganic light-emitting diodes (mini LEDs, in which the size of the chip contained therein is ranged from 100 μm to 300 μm), micro inorganic light-emitting diodes (micro LEDs, in which the size of the chip contained therein is ranged from 1 μm to 100 μm), or other display medium. 
     Furthermore, the display device made as described in any of the embodiments of the present disclosure as described previously can be co-used with a touch panel to form a touch display device. Meanwhile, a display device or touch display device may be applied to any electronic devices known in the art that need a display screen, such as displays, mobile phones, laptops, video cameras, still cameras, music players, mobile navigators, TV sets, and other electronic devices that display images. 
     Although the present disclosure has been explained in relation to its embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the disclosure as hereinafter claimed.