Light-emitting device

• US 8,493,295 B2
• Filed: 01/20/2011
• Issued: 07/23/2013
• Est. Priority Date: 02/29/2000
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Koyama, Jun, Osada, Mai
• Primary Examiner(s): ABDULSELAM, ABBAS I
• Application Number:
  US13/010,118
• Publication Number:
  US 20110109604A1
• Time in Patent Office: 915 Days
• Field of Search: 345/76, 345/82, 345/92, 345/94, 345/100, 345/208, 257/22, 257/66, 257/350, 315/169.3, 313/505
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile
• CPC Class Codes: H01L 29/78627 : with a significant overlap between the lightly doped drain and the gate electrode, e.g. GOLDD
• CPC Class Codes: H01L 29/78654 : Monocrystalline silicon transistors
• CPC Class Codes: H01L 29/7866 : Non-monocrystalline silicon transistors
• CPC Class Codes: H01L 29/78672 : Polycrystalline or microcrystalline silicon transistor
• CPC Class Codes: H01L 29/78696 : characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621
• CPC Class Codes: H10K 50/805 : Electrodes
• CPC Class Codes: H10K 59/00 : Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 59/12 : Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1201 : Manufacture or treatment
• CPC Class Codes: H10K 59/1213 : the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 : the pixel elements being capacitors
• CPC Class Codes: H10K 59/123 : Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/124 : Insulating layers formed between TFT elements and OLED elements
• CPC Class Codes: H10K 59/35 : comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 59/871 : Self-supporting sealing arrangements
• CPC Class Codes: H10K 59/8722 : Peripheral sealing arrangements, e.g. adhesives, sealants

Abstract

There is provided an EL light-emitting device with less uneven brightness. When a drain current of a plurality of current controlling TFTs is Id, a mobility is μ, a gate capacitance per unit area is Co, a maximum gate voltage is Vgs_(max), a channel width is W a channel length is L, an average value of a threshold voltage is Vth, a deviation from the average value of the threshold voltage is ΔVth, and a difference in emission brightness of a plurality of EL elements is within a range of ±n %, a semiconductor display device is characterized in that

$A=\frac{2\mathrm{Id}}{\mu *C_0}$ $\frac{A}{{\left({\mathrm{Vgs}}_{\left(\max \right)}-\mathrm{Vth}\right)}^2}\leqq \frac{W}{L}\leqq {\left(\sqrt{1+\frac{n}{100}}-1\right)}^2*\frac{A}{\Delta {\mathrm{Vth}}^2}$ $\Delta \mathrm{Vth}\leqq \left(\sqrt{1+\frac{n}{100}}-1\right)*\sqrt{A*L/W}.$

Claims

1. A display device comprising:

a first pixel comprising;

a first transistor comprising a first channel forming region, the first channel forming region having a first channel width and a first channel length; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second channel forming region, the second channel forming region having a second channel width and a second channel length; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length.

2. The display device according to claim 1, wherein each of the first transistor and the second transistor is a thin film transistor.

3. The display device according to claim 1, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

4. The display device according to claim 1, wherein each of the first transistor and the second transistor is a top-gate transistor.

5. The display device according to claim 1, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

6. The display device according to claim 1,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

7. The display device according to claim 1,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

8. The display device according to claim 1, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

9. An electronic apparatus having the display device according to claim 1, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

10. A display device comprising:

a first pixel comprising;

a first transistor comprising a first semiconductor film, a first gate insulating film, and a first gate electrode, wherein the first semiconductor film includes a first channel forming region having a first channel width and a first channel length, and wherein the first semiconductor film and the first gate electrode are overlapped with each other with the first gate insulating film interposed therebetween; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second semiconductor film, a second gate insulating film, and a second gate electrode, wherein the second semiconductor film includes a second channel forming region having a second channel width and a second channel length, and wherein the second semiconductor film and the second gate electrode are overlapped with each other with the second gate insulating film interposed therebetween; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length.

11. The display device according to claim 10, wherein each of the first transistor and the second transistor is a thin film transistor.

12. The display device according to claim 10, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

13. The display device according to claim 10, wherein each of the first transistor and the second transistor is a top-gate transistor.

14. The display device according to claim 10, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

15. The display device according to claim 10,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

16. The display device according to claim 10,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

17. The display device according to claim 10, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

18. An electronic apparatus having the display device according to claim 10, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

19. The display device according to claim 10, wherein the first gate electrode is formed from an element selected from the group consisting of Ta, W, Ti, Mo, Al, and Cu.

20. A display device comprising:

a first pixel comprising;

a first transistor comprising a first channel forming region, the first channel forming region having a first channel width and a first channel length; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second channel forming region, the second channel forming region having a second channel width and a second channel length; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length, and

wherein an emission color of the first pixel is different from that of the second pixel.

21. The display device according to claim 20, wherein each of the first transistor and the second transistor is a thin film transistor.

22. The display device according to claim 20, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

23. The display device according to claim 20, wherein each of the first transistor and the second transistor is a top-gate transistor.

24. The display device according to claim 20, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

25. The display device according to claim 20,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

26. The display device according to claim 20,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

27. The display device according to claim 20, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

28. An electronic apparatus having the display device according to claim 20, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

29. A display device comprising:

a first pixel comprising;

a first transistor comprising a first semiconductor film, a first gate insulating film, and a first gate electrode, wherein the first semiconductor film includes a first channel forming region having a first channel width and a first channel length, and wherein the first semiconductor film and the first gate electrode are overlapped with each other with the first gate insulating film interposed therebetween; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second semiconductor film, a second gate insulating film, and a second gate electrode, wherein the second semiconductor film includes a second channel forming region having a second channel width and a second channel length, and wherein the second semiconductor film and the second gate electrode are overlapped with each other with the second gate insulating film interposed therebetween; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length, and

wherein an emission color of the first pixel is different from that of the second pixel.

30. The display device according to claim 29, wherein each of the first transistor and the second transistor is a thin film transistor.

31. The display device according to claim 29, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

32. The display device according to claim 29, wherein each of the first transistor and the second transistor is a top-gate transistor.

33. The display device according to claim 29, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

34. The display device according to claim 29,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

35. The display device according to claim 29,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

36. The display device according to claim 29, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

37. An electronic apparatus having the display device according to claim 29, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

38. The display device according to claim 29, wherein the first gate electrode is formed from an element selected from the group consisting of Ta, W, Ti, Mo, Al, and Cu.

39. A display device comprising:

a first pixel comprising;

a first transistor comprising a first channel forming region, the first channel forming region having a first channel width and a first channel length;

a first capacitor electrically connected to the first transistor; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second channel forming region, the second channel forming region having a second channel width and a second channel length;

a second capacitor electrically connected to the second transistor; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length.

40. The display device according to claim 39, wherein each of the first transistor and the second transistor is a thin film transistor.

41. The display device according to claim 39, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

42. The display device according to claim 39, wherein each of the first transistor and the second transistor is a top-gate transistor.

43. The display device according to claim 39, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

44. The display device according to claim 39,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

45. The display device according to claim 39,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

46. The display device according to claim 39, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

47. An electronic apparatus having the display device according to claim 39, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

48. A display device comprising:

a first pixel comprising;

a first transistor comprising a first semiconductor film, a first gate insulating film, and a first gate electrode, wherein the first semiconductor film includes a first channel forming region having a first channel width and a first channel length, and wherein the first semiconductor film and the first gate electrode are overlapped with each other with the first gate insulating film interposed therebetween;

a first capacitor electrically connected to the first transistor; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second semiconductor film, a second gate insulating film, and a second gate electrode, wherein the second semiconductor film includes a second channel forming region having a second channel width and a second channel length, and wherein the second semiconductor film and the second gate electrode are overlapped with each other with the second gate insulating film interposed therebetween;

a second capacitor electrically connected to the second transistor; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length.

49. The display device according to claim 48, wherein each of the first transistor and the second transistor is a thin film transistor.

50. The display device according to claim 48, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

51. The display device according to claim 48, wherein each of the first transistor and the second transistor is a top-gate transistor.

52. The display device according to claim 48, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

53. The display device according to claim 48,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

54. The display device according to claim 48,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

55. The display device according to claim 48, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

56. An electronic apparatus having the display device according to claim 48, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

57. The display device according to claim 48, wherein the first gate electrode is formed from an element selected from the group consisting of Ta, W, Ti, Mo, Al, and Cu.

58. A display device comprising:

a first pixel comprising;

a first transistor comprising a first channel forming region, the first channel forming region having a first channel width and a first channel length;

a first capacitor electrically connected to the first transistor; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second channel forming region, the second channel forming region having a second channel width and a second channel length;

a second capacitor electrically connected to the second transistor; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length, and

wherein an emission color of the first pixel is different from that of the second pixel.

59. The display device according to claim 58, wherein each of the first transistor and the second transistor is a thin film transistor.

60. The display device according to claim 58, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

61. The display device according to claim 58, wherein each of the first transistor and the second transistor is a top-gate transistor.

62. The display device according to claim 58, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

63. The display device according to claim 58,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

64. The display device according to claim 58,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

65. The display device according to claim 58, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

66. An electronic apparatus having the display device according to claim 58, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

67. A display device comprising:

a first pixel comprising;

a first transistor comprising a first semiconductor film, a first gate insulating film, and a first gate electrode, wherein the first semiconductor film includes a first channel forming region having a first channel width and a first channel length, and wherein the first semiconductor film and the first gate electrode are overlapped with each other with the first gate insulating film interposed therebetween;

a first capacitor electrically connected to the first transistor; and

a first pixel electrode electrically connected to the first transistor;

a second pixel comprising;

a second transistor comprising a second semiconductor film, a second gate insulating film, and a second gate electrode, wherein the second semiconductor film includes a second channel forming region having a second channel width and a second channel length, and wherein the second semiconductor film and the second gate electrode are overlapped with each other with the second gate insulating film interposed therebetween;

a second capacitor electrically connected to the second transistor; and

a second pixel electrode electrically connected to the second transistor;

a flattening layer interposed between the first channel forming region and the first pixel electrode; and

a layer including an organic material, the layer being over and in contact with the first pixel electrode,

wherein a ratio of the first channel width to the first channel length is different from a ratio of the second channel width to the second channel length.

68. The display device according to claim 67, wherein each of the first transistor and the second transistor is a thin film transistor.

69. The display device according to claim 67, wherein each of the first transistor and the second transistor is a current controlling thin film transistor.

70. The display device according to claim 67, wherein each of the first transistor and the second transistor is a top-gate transistor.

71. The display device according to claim 67, wherein each of the first transistor and the second transistor includes a crystalline semiconductor film.

72. The display device according to claim 67,

wherein the first pixel further comprises a first EL element, and

wherein the second pixel further comprises a second EL element.

73. The display device according to claim 67,

wherein the first pixel further comprises a first switching transistor, and

wherein the second pixel further comprises a second switching transistor.

74. The display device according to claim 67, wherein the ratio of the first channel width to the first channel length is equal to or larger than 2.26×

10<sup>−

3</sup> and equal to or smaller than 0.214.

75. An electronic apparatus having the display device according to claim 67, wherein the electronic apparatus is one selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation system, an audio reproduction device, a notebook personal computer, a game equipment, a mobile computer, a mobile telephone, a mobile game equipment, an electronic book, and an image reproduction device provided with a recording medium.

76. The display device according to claim 67, wherein the first gate electrode is formed from an element selected from the group consisting of Ta, W, Ti, Mo, Al, and Cu.