Patent Publication Number: US-2015060780-A1

Title: Organic light-emitting display device

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwanese application Serial Number 102132049, filed Sep. 5, 2013, the entirety of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an organic light-emitting display device. 
     2. Description of Related Art 
     There has been rapid progress in organic light-emitting diode (OLED) technologies in recent years. The advantages of OLEDs include high brightness, high contrast and wide view angle. The OLED is a type of light-emitting diode (LED) and has an organic electroluminescent layer therein. The major material of the organic electroluminescent layer is an organic compound. When current passes through the organic compound, the organic compound emits light. The mostly seen problem of OLEDs is the deterioration of the organic light-emitting layer. The organic light-emitting layer reacts with oxygen and moisture easily, and thereby the performance is degraded. Accordingly, the best condition is that the organic light-emitting layer may be completely enclosed inside the OLED device and isolated from the environment. If the penetration of oxygen and moisture into the OLED device may be prevented thoroughly, the lifespan of the OLED device will be extended remarkably. However, it is difficult to develop an assembly technique that thoroughly blocks off oxygen and moisture. Therefore, an important issue in OLED industry is how to develop an effective and reliable encapsulating structure of the OLED. 
     SUMMARY 
     According to one aspect of the present disclosure, an organic light-emitting display device is provided. The organic light-emitting display device is capable of preventing the organic light-emitting layer therein from deterioration and/or damage. The organic light-emitting display device includes an active array substrate, an encapsulating layer, an organic light-emitting layer, an absorption layer and a sealant. The active array substrate is configured to drive the organic light-emitting layer and is opposite to the encapsulating layer. The encapsulating layer has an inner surface facing the active array substrate. The organic light-emitting layer is disposed on the active array substrate. The absorption layer is positioned on the inner surface of the encapsulating layer, and is configured to absorb at least one of moisture and oxygen. The sealant is disposed between the active array substrate and the encapsulating layer, and encircles the organic light-emitting layer and the absorption layer. 
     According to one embodiment of the present disclosure, the encapsulating layer includes a polymer layer and an inorganic barrier layer. The inorganic barrier layer is configured to block the penetration of at least one of moisture and oxygen. The absorption layer is positioned on the inorganic barrier layer. 
     According to one embodiment of the present disclosure, the polymer layer is about 0.005 to about 0.5 mm in thickness. 
     According to one embodiment of the present disclosure, the inorganic barrier layer includes silicon oxide, silicon nitride, or a combination thereof. 
     According to one embodiment of the present disclosure, the encapsulating layer has a concavity, and the absorption layer is positioned inside the concavity. 
     According to one embodiment of the present disclosure, the organic light-emitting display device further includes a polymeric planarization layer which covers the absorption layer. The polymeric planarization layer allows at least one of moisture and oxygen to penetrate therethrough. 
     According to one embodiment of the present disclosure, the absorption layer includes a resin layer, and a plurality of absorbent particles dispersed therein. The absorbent particle contains at least one material selected from the group consisting of calcium chloride, cobalt chloride, calcium sulfate, copper sulfate, calcium oxide, zeolite, silicone, activated aluminum oxide and a combination thereof. 
     According to one embodiment of the present disclosure, the encapsulating layer is a flexible glass substrate having a thickness of about 10 μm to about 300 μm. 
     According to one embodiment of the present disclosure, the flexible glass substrate has a concavity, and the absorption layer is positioned inside the concavity. 
     According to one embodiment of the present disclosure, the organic light-emitting display device further includes a polymeric planarization layer which covers the absorption layer. The polymeric planarization layer allows at least one of moisture and oxygen to penetrate therethrough. 
     According to one embodiment of the present disclosure, the organic light-emitting display device further includes a patterned spacing layer which is positioned on the flexible glass substrate, and the patterned spacing layer has at least one opening, and the absorption layer is disposed inside the opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be more fully understood by reading the following detailed description of the embodiments, with reference made to the accompanying drawings as follows: 
         FIG. 1A  is a top view schematically illustrating an organic light-emitting display device according to one embodiment of the present disclosure; 
         FIG. 1B  is a cross-sectional view along line B-B′ in  FIG. 1A ; 
         FIG. 1C  schematically depicts an absorption layer according to one embodiment of the present disclosure; 
         FIG. 2  is a cross-sectional view schematically illustrating an organic light-emitting display device according to another embodiment of the present disclosure; 
         FIG. 3  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure; 
         FIG. 4  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure; 
         FIG. 5  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure; 
         FIG. 6  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure; 
         FIGS. 7-9  are cross-sectional views schematically illustrating organic light-emitting display devices according to various embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings. 
       FIG. 1  is a top view schematically illustrating an organic light-emitting display device  100  according to one embodiment of the present disclosure, and  FIG. 1B  is a cross-sectional view along line B-B′ in  FIG. 1A . The organic light-emitting display device  100  includes an active array substrate  110 , an encapsulating layer  120 , an organic light-emitting layer  130 , an absorption layer  140 , and a sealant  150 . 
     The active array substrate  110  includes a plurality of pixel structures (not shown in  FIGS. 1A and 1B ) provided for driving the organic light-emitting layer  130  on the substrate to emit light. There is no specific limitation to the pixel structure of the active array substrate  110 , and any pixel structure applicable to the organic light-emitting diode (OLED) may be employed in the present disclosure. In one example, the pixel structure includes a gate line, a data line, a capacitor line, a driving line, and two thin film transistors, which is known in the art. 
     The organic light-emitting layer  130  is disposed on the active array substrate  110  and is positioned between the active array substrate  110  and the encapsulating layer  120 . In general, the organic light-emitting layer  130  includes a plurality of patterned light-emitting layers that emit lights with various colors, such as a red patterned light-emitting layer, a green patterned light-emitting layer, and a blue patterned light-emitting layer. Any material suitable for the organic light-emitting layer  130  may be utilized in the present disclosure. The active array substrate  110  is provided for controlling the light-emitting states of the patterned light-emitting layers such that the organic light-emitting display device  100  displays a predetermined image according to the input data. 
     The encapsulating layer  120  and the active array substrate  110  are disposed opposite to each other. In particular, the encapsulating layer  120  is substantially parallel to the active array substrate  110 , and the encapsulating layer  120  has an inner surface  121  facing the active array substrate  110 . In one embodiment, the encapsulating layer  120  is a super thin glass with a thickness d 1  of about 10 μm to about 300 μm, specifically about 30 μm to about 100 μm. The super thin glass is flexible and bendable, which is different from the traditional glass in mechanical properties, so that the super thin glass is a type of flexible glass substrate. In some embodiments, the encapsulating layer  120  is a composite-layered structure including a polymer layer and an inorganic barrier layer stacked thereon. More detailed description of the encapsulating layer  120  is provided hereinafter. 
     The sealant  150  is disposed between the active array substrate  110  and the encapsulating layer  120 , and encircles the organic light-emitting layer  130  and the absorption layer  140 . In specifics, the sealant  150  is configured to adhere the active array substrate  110  and the encapsulating layer  120  together, and further an enclosed space  155  is formed between the sealant  150 , the active array substrate  110  and the encapsulating layer  120 . The organic light-emitting layer  130  and the absorption layer  140  are disposed inside the enclosed space  155 . 
     Either moisture or oxygen in the environment has an unfavorable influence on the organic light-emitting layer  130 . Many researches show that H 2 O molecules and O 2  molecules react with the organic light-emitting layer  130 , and thereby deteriorate the organic light-emitting layer  130 . Accordingly, the active array substrate  110 , the sealant  150 , and the encapsulating layer  120  mentioned above are bonded together in an environment free of moisture and oxygen such that the enclosed space is free of moisture and oxygen. Nevertheless, the organic light-emitting layer  130  is still deteriorated since moisture and/or oxygen in the environment penetrate through the sealant  150  and diffuse into the enclosed space  155 . 
     The absorption layer  140  is positioned on the inner surface  121  of the encapsulating layer  120  and provided for absorbing at least one of moisture and oxygen in the enclosed space  155 . To be specific, the absorption layer  140  is capable of absorbing moisture and/or oxygen diffused into the enclosed space  155  from the environment, and significantly the absorption layer  140  is not in contact with the organic light-emitting layer  130 . In the embodiment illustrated in  FIG. 1B , a gap is formed between the absorption layer  140  and the organic light-emitting layer  130 . In one embodiment, the absorption layer  140  includes a resin layer  142  and a plurality of absorbent particles  144 , as shown in  FIG. 1C . The absorbent particles  144  are dispersed in the resin layer  142 . The resin layer  142  allows moisture and/or oxygen to diffuse and penetrate therethrough, and reach the absorbent particles  144 . Consequently, although the absorbent particles  144  are surrounded by the resin layer  142 , the absorbent particles  144  are still capable of absorbing moisture and/or oxygen in the enclosed space. The material of the resin layer  142  may be, for example, ethyl cellulose, epoxy resin, polymethyl methacrylate (PMMA), polymethylglutarimide, (PMGI) or phenol formaldehyde resin (DNQ/Novolac). Various approaches may be utilized to form the absorption layer  140 . For instance, screen-printing process, concave plate printing techniques, or other processes may be employed to form the patterned absorption layer  140 . In some embodiments, the resin layer  142  includes a photosensitive material, and thus the absorption layer  140  may be formed with a certain pattern by photolithography techniques involving exposure and development processes. The material of the absorbent particle  144  may be, for example, calcium chloride, cobalt chloride, calcium sulfate, copper sulfate, calcium oxide, zeolite, silicone, activated aluminum oxide and a combination thereof. 
     In one specific example, after the organic light-emitting layer  130  and the absorption layer  140  are formed respectively on the active array substrate  110  and the encapsulating layer  120 , the active array substrate  110  with the organic light-emitting layer  130  and the encapsulating layer  120  with the absorption layer  140  are bonded together. For example, liquid glue (the sealant  150 ) may be coated on the active array substrate  110  (or the encapsulating layer  120 ). Thereafter, the encapsulating layer  120  (or the active array substrate  110 ) is attached onto the sealant  150  on the active array substrate  110  for the encapsulating layer  120 ), and then the liquid glue is cured and converted into the sealant  150 . In one embodiment, when the encapsulating layer  120  is a flexible substrate, the encapsulating layer  120  may be temperately adhered to a rigid carrier  160  in advance. For example, the flexible encapsulating layer  120  may be temperately adhered to the rigid carrier  160  by an adhesive layer  162 , and then is bonded to the active array substrate  110  through the sealant  150 . When the sealant  150  is cured such that the encapsulating layer  120  and the active array substrate  110  are firmly bonded together, the rigid carrier  160  and the adhesive layer  162  are detached and separated from the flexible encapsulating layer  120 , and thereby forming the organic light-emitting display device  100  shown in  FIG. 1B . 
       FIG. 2  is a cross-sectional view schematically illustrating an organic light-emitting display device according to another embodiment of the present disclosure. The difference between this embodiment and the one shown in  FIG. 1B  is that the encapsulating layer  120  has a concavity  122  in which the absorption layer  140  is disposed. When the encapsulating layer  120  is a flexible substrate, the absorption layer  140  on the encapsulating layer  120  possibly comes into contact with the organic light-emitting layer  130  due to the deformation of the encapsulating layer  120 . In order to avoid this phenomena, the depth a of the concavity  122  is preferably greater than or equal to the thickness b of the absorption layer  140 . Accordingly, the concavity  122  may prevent the absorption layer  140  from touching the organic light-emitting layer  130  when the encapsulating layer  120  is deformed or bended by force. 
       FIG. 3  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure. The present embodiment differs from the one shown in  FIG. 1B  in that the organic light-emitting display device of this embodiment further includes a polymeric planarization layer  170 . The polymeric planarization layer  170  is formed on the absorption layer  140  and covers the absorption layer  140 . Moisture and/or oxygen may diffuse and penetrate through the polymeric planarization layer  170  and reach the absorption layer  140 . Stated different, the material of the polymeric planarization layer  170  is featured in allowing moisture and/or oxygen to penetrate and pass therethrough. Accordingly, although the polymeric planarization layer  170  covers the absorption layer  140 , the absorption layer  140  may still absorb moisture and/or oxygen. Moreover, the polymeric planarization layer  170  may prevent the absorption layer  140  from touching the organic light-emitting layer  130 . The absorption layer  140  includes, for example, calcium chloride, cobalt chloride, calcium sulfate, copper sulfate, calcium oxide, zeolite, silicone, activated aluminum oxide and a combination thereof. 
       FIG. 4  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure. The difference between this embodiment and the one shown in  FIG. 1B  is that the organic light-emitting display device of this embodiment further includes a patterned spacing layer  180 . The patterned spacing layer  180  is disposed on the encapsulating layer  120 , and has an opening  182  exposing a portion of the encapsulating layer  120 . The absorption layer  140  is formed inside the opening  182 . The patterned spacing layer  180  may be made of, for example, a positive photoresist material or a negative photoresist material. In some examples, the opposite sides of the sealant  150  are respectively adhered to the patterned spacing layer  180  and the active array substrate  110 . The patterned spacing layer  180  is provided for increasing the distance between the absorption layer  140  and the organic light-emitting layer  130 . 
       FIG. 5  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure. The difference between this embodiment and the one shown in  FIG. 4  is that the patterned spacing layer  180  has a plurality of openings  182 , and the patterned spacing layer  180  is positioned right above the organic light-emitting layer  130 . Furthermore, the absorption layer  140  is formed in these openings  182 , so that the absorption layer  140  has a predetermined pattern. The thickness H of the patterned spacing layer  180  is greater than the thickness T of the absorption layer  140 . When the encapsulating layer  120  is deformed or bended, the patterned spacing layer  180  touches the organic light-emitting layer  130  and prevents the absorption layer  140  from directly contact with the organic light-emitting layer  130 . 
       FIG. 6  is a cross-sectional view schematically illustrating an organic light-emitting display device according to still another embodiment of the present disclosure. This embodiment is similar to the one shown in  FIG. 4 , but differs therefrom in that the patterned spacing layer  180  itself is adhesive and capable of being cured. The patterned spacing layer  180  performs the function of the sealant  150 , and replaces the sealant  150  shown in  FIG. 4 . In other words, the patterned spacing layer  180  functions as the sealant as well in the embodiment shown in  FIG. 6 . 
       FIGS. 7-9  are cross-sectional views schematically illustrating organic light-emitting display devices according to various embodiments of the present disclosure. In the embodiment shown in  FIG. 7 , the encapsulating layer  120  includes a polymer layer  124  and an inorganic barrier layer  126 . The polymer layer  124  and the inorganic barrier layer  126  are in a stacked structure. The polymer layer  124  is positioned on an outer surface of the organic light-emitting display device, while the inorganic barrier layer  126  is on an inner surface of the organic light-emitting display device. The inorganic barrier layer  126  is provided for preventing at least one of moisture and oxygen from penetrating into the organic light-emitting display device. The absorption layer  140  is formed on the inorganic barrier layer  126 . The thickness d 2  of the polymer layer  124  may be, for example, about 0.005 to about 0.05 mm. The material of the polymer layer  124  may be, for example, polyimide (PI). The material of the inorganic barrier layer  126  may be, for example, silicon oxide, silicon nitride, or a combination thereof. The encapsulating layer  120  includes a concavity  128  in which the absorption layer  140  is disposed. In specifics, the polymer layer  124  and the inorganic barrier layer  126  may be in sequence formed on a carrier plate  160 . Afterwards, the carrier plate  160  with the polymer layer  124  and the inorganic barrier layer  126  is bonded to the active array substrate  110 . After the sealant  150  is cured, the carrier plate  160  is removed from the polymer layer  124  so as to form the encapsulating layer  120 . The details of the active array substrate  110 , the organic light-emitting layer  130 , and the sealant  150  may be the same as these described in any of the embodiments hereinbefore, and therefore the description is omitted to avoid repetition. 
     The embodiment depicted in  FIG. 8  is similar to the one shown in  FIG. 7 , but the difference there between is that the organic light-emitting display device depicted in  FIG. 8  further includes a polymeric planarization layer  190 . The polymeric planarization layer  190  covers the absorption layer  140  and the concavity  128  (shown in  FIG. 7 ) and makes an even surface. The polymeric planarization layer  190  is positioned between the organic light-emitting layer  130  and the absorption layer  140 , and moisture and/or oxygen may penetrate and diffuse through the polymeric planarization layer  190 . In other words, the material of the polymeric polymeric planarization layer  190  is featured in allowing moisture and/or oxygen to penetrate and pass therethrough. Therefore, although the polymeric planarization layer  190  covers the absorption layer  140 , the absorption layer  140  may still absorb moisture and/or oxygen. Besides, the polymeric planarization layer  190  may prevent the absorption layer  140  from contact with the organic light-emitting layer  130  directly. 
     The embodiment depicted in  FIG. 9  is similar to the one shown in  FIG. 8 , but the difference there between is that the encapsulating layer  120  does not include the concavity  128 . The absorption layer  140  is formed on the inorganic barrier layer  126 . The details of the active array substrate  110 , the organic light-emitting layer  130 , and the sealant  150  may the same as these described in any of the embodiments hereinbefore, and therefore the description is omitted to avoid repetition. 
     It will be apparent to those skilled in the art that various modifications and variations may be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.