JP2011035087A - Organic el panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL panel that enables light extinction by which brightness dispersion and chromaticity variation are small, even when the light extinction rate is high and that can improve salability as a light-emitting apparatus. <P>SOLUTION: The organic EL panel has a light-emitting portion, having a pair of electrodes 2 and 4 formed on a support substrate 1 and at least one of which has translucency, and an organic light-emitting layer formed between the electrodes 2 and 4 and an electrochromic element 6 provided on the light extracting side. A transmission spectrum peak wavelength at the voltage application of the electrochromic element 6 is different from a light-emitting spectrum peak wavelength of the light-emitting portion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic EL (electroluminescence) panel used for a display device or a lighting device.

  2. Description of the Related Art Conventionally, an organic EL panel including an organic EL element that is a self-luminous element formed of an organic material has, for example, a function of having a first electrode made of indium tin oxide (ITO) serving as an anode and at least an organic light emitting layer. A layer, a non-translucent second electrode made of aluminum (Al) or the like serving as a cathode, and a layer sequentially laminated on a translucent support substrate are known (for example, see Patent Document 1). Such an organic EL element emits light by injecting holes from the first electrode and injecting electrons from the second electrode, and the holes and electrons recombine in the light emitting layer. In recent years, organic EL panels have attracted attention as self-luminous panels that can be thinned, and research and development have been conducted for use as display devices such as flat panel displays and illumination devices such as surface light sources.

  Further, an organic EL panel as a display device or a lighting device needs to be dimmed according to the situation, and a dimming method by PWM modulation or PAM modulation of a driving pulse of the organic EL panel is known (for example, patent) Reference 2). According to PWM modulation, the organic EL element is dimmed by adjusting the wavelength of the ON waveform of the drive pulse, and according to PAM modulation, the organic EL element is adjusted by adjusting the amplitude of the ON waveform of the drive pulse. Dimmed.

JP 59-194393 A JP 2006-58467 A JP-A-3-155090

  However, in the above-described dimming method using PWM modulation or PAM modulation, when the dimming rate is increased and the luminance becomes 10% or less of the normal (maximum) luminance, variation in luminance is caused by variation in organic EL elements and IC. There was a problem of becoming prominent. It is known that the luminance difference becomes noticeable during low current driving or low voltage driving due to the characteristics of the organic EL element, which is affected by variations in driving voltage and light emission efficiency of the organic EL element. For this reason, the dimming rate is limited in the dimming method using PWM modulation or PAM modulation. On the other hand, Patent Document 3 proposes a dimming method using an electrochromic (EC) element. However, the EC element having high dimming performance has a peak in the transmission spectrum, and there is a problem that the dimming is not effectively performed only by using the EC element. In particular, white light emitted by organic EL elements is mostly obtained by mixing multiple wavelengths, and the emission color changes unless the balance between the transmission spectrum of the EC element and the emission spectrum of the organic EL element is taken into consideration. As a result, the light is not effectively attenuated.

  The present invention has been made in view of this problem, and enables dimming with little variation in luminance and change in chromaticity even when the dimming rate is high, thereby improving the merchantability as a light emitting device. An object of the present invention is to provide a possible organic EL panel.

  In order to solve the above-described problems, the present invention provides a light-emitting unit including a pair of electrodes formed on a support substrate and at least one of which is light-transmitting, and an organic light-emitting layer formed between the electrodes, and a light extraction side. An electrochromic element disposed on the electrochromic element, wherein a transmission spectrum peak wavelength when a voltage is applied to the electrochromic element is different from an emission spectrum peak wavelength of the light emitting part. To do.

  The emission spectrum peak wavelength of the light emitting part is 500 nm or more and 700 nm or less, and the transmission spectrum peak wavelength when the voltage is applied to the electrochromic device is 300 nm or more and less than 500 nm.

  In addition, the emission spectrum peak wavelength of the light emitting portion is 300 nm to 500 nm, and the transmission spectrum peak wavelength of the electrochromic device when a voltage is applied is greater than 500 nm and 700 nm or less.

  Further, the light emitting section has a plurality of emission spectrum peak wavelengths, and the transmission spectrum peak wavelength when the electrochromic device is applied with a voltage is different from any of the emission spectrum peak wavelengths.

  The transmission spectrum peak wavelength when the voltage of the electrochromic element is applied is different from the emission spectrum peak wavelength of the light emitting part by 50 nm or more.

  The present invention relates to an organic EL panel used in a display device or a lighting device, and enables dimming with little variation in luminance and chromaticity even when the dimming rate is high, thereby improving the merchantability as a light emitting device. It is possible to make it.

Sectional drawing which shows the organic electroluminescent panel which is embodiment of this invention. Sectional drawing which shows the organic electroluminescent panel which is other embodiment of this invention. Sectional drawing which shows the organic electroluminescent panel which is other embodiment of this invention. Sectional drawing which shows the organic electroluminescent panel which is other embodiment of this invention. Sectional drawing which shows the organic electroluminescent panel which is other embodiment of this invention. The figure which shows the evaluation result of the Example and comparative example of this invention. Sectional drawing which shows the organic electroluminescent panel which is the comparative example 1. FIG. The figure which shows the emission spectrum of the comparative example 1. Sectional drawing which shows the organic electroluminescent panel which is the comparative example 2. FIG. The figure which shows the transmission spectrum of EC element of the comparative example 2. FIG. The figure which shows the emission spectrum at the time of dimming of the comparative example 2. FIG. FIG. 4 shows an emission spectrum of Example 1. The figure which shows the transmission spectrum of EC element of Example 1. FIG. FIG. 4 shows an emission spectrum at the time of dimming in Example 1. The figure which shows the transmission spectrum of EC element of Example 2. FIG. The figure which shows the emission spectrum at the time of dimming of Example 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The organic EL panel includes a support substrate 1, a first electrode 2, a functional layer 3, a second electrode 4, a sealing substrate 5, and an EC element 6.

  The support substrate 1 has a rectangular shape and is formed of a translucent glass substrate.

  The first electrode 2 serves as an anode for injecting holes into the functional layer 3, and is made of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO) or the like on the support substrate 1. The translucent conductive material is formed in a layer shape by means such as sputtering, and is patterned into a predetermined shape by means such as photoetching.

  The functional layer 3 only needs to have at least an organic light emitting layer that emits light by recombination of holes and electrons. In the embodiment of the present invention, a hole injection layer, a hole transport layer, an organic light emitting layer, and The electron transport layer is formed by sequentially laminating. In addition, when obtaining white light emission, a plurality of organic light emitting layers having different emission spectrum peaks are provided (for example, amber light emitting layer and blue light emitting layer), and white is obtained by mixing colors of the light emitting layers.

  The second electrode 4 serves as a cathode for injecting electrons into the functional layer 3, and is a reflective electrode formed by layering a low-resistance conductive material such as Al on the functional layer 3 by means such as vapor deposition. It is.

  As described above, the light emitting portion (organic EL element) is provided by sequentially stacking the first electrode 2, the functional layer 3, and the second electrode 4 on the support substrate 1.

  The sealing substrate 5 is made of a glass material, and is formed in a concave shape in the present embodiment. The sealing substrate 5 has a peripheral wall portion 5a bonded and fixed to the support substrate 1 via an ultraviolet curable adhesive 7 to constitute a storage space for hermetically storing the light emitting portion. In the storage space, it is desirable that a hygroscopic agent that adsorbs moisture contained in the storage space and the light emitting unit is disposed.

  The EC element 6 is formed by sequentially laminating a reduction color layer, a solid electrolyte layer, and an oxidation color layer between a pair of transparent electrodes made of, for example, ITO, IZO, or AZO, and the light emitting layer of the support substrate 1 is formed. It is formed on a surface opposite to the formed surface. As a manufacturing method of the EC element 6, for example, one of the transparent electrodes is formed on the support substrate 1 by a sputtering method, and the reduced coloring layer is formed on the transparent electrode by an electron beam volume method. A layer and an oxidation coloring layer are sequentially formed by an ion plating method, and the other transparent electrode is formed by a sputtering method. Depending on the constituent material of each layer, other methods such as a vacuum deposition method, a sputtering method, and a sol-gel method can be used as the film formation method. The EC element 6 is colored by applying a voltage between both electrodes, and the transmittance can be controlled.

  The organic EL panel is constituted by the above-described parts. Such an organic EL panel is a so-called bottom emission type organic EL panel, and emits light emitted from the light emitting portion from the support substrate 1 through the EC element 6.

  Here, in order to optimize the dimming by the EC element 6, the EC element 6 has a transmission spectrum peak wavelength different from the emission spectrum peak wavelength of the light emitting section when the voltage is applied. More preferably, the difference between the transmission spectrum peak wavelength when the voltage of the EC element 6 is applied and the emission spectrum peak wavelength of the light emitting part is 50 nm or more.

  Further, when the emission spectrum peak wavelength of the light emitting part is 500 nm or more and 700 nm or less, the EC element 6 has a transmission spectrum peak wavelength of 300 nm or more and less than 500 nm when a voltage is applied.

  Further, when the emission spectrum peak wavelength of the light emitting portion is 300 nm or more and 500 nm or less, the EC element 6 is used whose transmission spectrum peak wavelength when voltage is applied is larger than 500 nm and 700 nm or less.

  Further, when there are a plurality of emission spectrum peak wavelengths of the light emitting part, the EC element 6 uses a transmission spectrum peak wavelength different from any emission spectrum peak wavelength when a voltage is applied.

  The location where the EC element 6 is disposed is not limited to the present embodiment, and various modifications can be made as long as the light from the light emitting portion can be reduced. FIG. 2 shows a configuration in which the EC element 6 is provided on the surface of the support substrate 1 on which the light emitting part is formed. An insulating film 8 is formed between the EC element 6 and the first electrode 2. Such an organic EL panel is a bottom emission type organic EL panel, can be dimmed by the EC element 6, and can be protected by the sealing member 5 together with the light emitting portion. FIG. 3 shows a configuration in which the EC element 6 is formed on the light emitting portion, and an insulating film 8 is formed between the second electrode 4 and the EC element 6. Such an organic EL panel is a so-called top emission type organic EL panel, can be dimmed by the EC element 6, and can be protected by the sealing member 5 together with the light emitting portion. FIG. 4 shows a configuration in which the EC element 6 is provided on the surface of the sealing member 5 facing the light emitting portion. Such an organic EL panel is a top emission type organic EL panel, can be dimmed by the EC element 6, and can be protected by the sealing member 5 together with the light emitting portion. FIG. 5 shows a configuration in which the EC element 6 is provided on the outer surface of the sealing member 5. Such an organic EL panel is a top emission type organic EL panel and can be dimmed by an EC element.

Hereinafter, specific effects of the present invention will be described with reference to comparative examples and examples. As an evaluation method of each comparative example and example, the target value of the light emission luminance is set to 100 cd / m ² and the state driven by the pulse power source is set to a driving condition of 100% (initial luminance). %, 2 to 5% (10 cd / m ² , 2 to 5 cd / m ² ), and the emission luminance and chromaticity were measured. In addition, five panels were prepared for confirmation of variation, and the above-described emission luminance and emission chromaticity were measured. Note that optimization by changing the pulse conditions or the like is not performed during measurement of each panel. Moreover, the average value of five panels was recorded about luminescent chromaticity. FIG. 6 shows the evaluation results of the comparative example and the example.

(Comparative Example 1)
FIG. 7 shows an organic EL panel as a comparative example 1 in which no EC element is provided as in the prior art.
Comparative Example 1 has an amber light emitting layer and a blue light emitting layer as the organic light emitting layer, and obtains white light emission by color mixture, has the emission spectrum shown in FIG. 8, and the emission spectrum peak wavelengths are around 400 nm and 650 nm. There are two wavelengths in the vicinity. As the dimming method, dimming by PWM modulation and PAM modulation of the drive pulse was performed. As shown in FIG. 6, the comparative example 1 increases the dimming rate, the luminance difference gradually increases when the light emission is aimed at 10% and 2%, and the luminance difference gradually increases. Then, the variation with respect to the target value is ± 40%, and the difference between the minimum value and the maximum value is 80%, which is not preferable because the luminance difference can be visually recognized when the panels are arranged.

(Comparative Example 2)
FIG. 9 shows an organic EL panel as a comparative example 2 in which EC elements 9 having different conditions from the present invention are arranged on a support substrate 1. The white organic EL panel is the same as that of Comparative Example 1 except that the EC element 9 is provided. As a dimming method, the EC element 9 was used for dimming. FIG. 10 shows the transmission spectrum when the EC element 9 is decolored and colored. A voltage of −3 V was applied during decoloring, and a voltage of 3 V was applied during coloring. The EC element has the lowest transmittance at a practical level when 3V is applied. As shown in FIG. 10, the transmission spectrum peak wavelength when the EC element 9 is colored is around 400 nm and overlaps with the emission spectrum peak wavelength of the light emitting portion. FIG. 11 shows an emission spectrum of Comparative Example 2 that is dimmed using the EC element 9. According to FIG. 11, although there is no problem when the EC element 9 is decolored, light emission near 650 nm is sufficiently reduced when the EC element 9 is colored, which is dimming, whereas light emission near 400 nm is emitted. It can be seen that dimming is insufficient. Therefore, as shown in FIG. 6, the comparative example 2 is not preferable as a white organic EL panel because the chromaticity changes to blue when dimming. In addition, the dimming performance is limited to the light emission luminance target value of 10% because the light emission near 400 nm is insufficiently dimmed, and the light reduction rate of the target value of 2 to 5%. High dimming was not possible.

  Example 1 is the organic EL panel shown in the above-described embodiment, and is an organic EL panel in which EC elements 6 are arranged on a support substrate 1 as shown in FIG. Example 1 has an amber color light emitting layer as an organic light emitting layer and obtains amber color light emission. The light emitting part has an emission spectrum shown in FIG. 12, and an emission spectrum peak wavelength is one wavelength around 650 nm. It has become. As a dimming method, dimming was performed using the EC element 6. FIG. 13 shows the transmission spectrum of the EC element 6 in Example 1 when decolored and colored. The voltage application conditions during decoloring and coloring are the same as in Comparative Example 2. As shown in FIG. 13, the transmission spectrum peak wavelength when the EC element 6 is colored is around 400 nm, which is different from the emission spectrum peak wavelength of the light emitting portion. FIG. 14 shows the emission spectrum of Example 1 when the EC element 6 is disposed and the light is reduced. FIG. 14 shows that the emission intensity was about 18 when the EC element 6 was decolored, but the emission intensity was reduced to 0.5 or less when the EC element 6 was colored. The dimming effect at this time had a high dimming rate with an emission luminance of about 2%. Further, as shown in FIG. 6, in Example 1, the variation with respect to the target value is ± 2% at the time of dimming when the target value of the light emission luminance is 10%, and ± 10% at the time of dimming when the target value is 2%. Thus, the variation with respect to Comparative Example 1 could be greatly improved. It should be noted that the dimming with the target value of the emission luminance of 10% could be performed when a voltage of 2.5 V was applied to the EC element 6. Further, as for chromaticity, a large change in chromaticity as in Comparative Example 2 is not confirmed between the target value of 100% and 2%, and a substantially constant emission color is maintained, which is preferable. When the emission spectrum peak wavelength of the light emitting part is around 400 nm, the same effect as in Example 1 can be obtained by applying an EC element 6 having a transmission spectrum peak wavelength of 500 nm or more when colored. It was confirmed that

  Example 2 is the organic EL panel shown in the above-described embodiment, and is an organic EL panel in which EC elements 6 are arranged on the support substrate 1 as shown in FIG. Example 2 has an amber light emitting layer and a blue light emitting layer, and obtains white light emission by color mixing. The light emitting part has an emission spectrum similar to that of Comparative Example 1, and an emission spectrum peak wavelength is around 400 nm. And two wavelengths near 650 nm. As a dimming method, dimming was performed using the EC element 6. FIG. 15 shows the transmission spectrum when the EC element 6 in Example 2 is decolored and colored. The voltage application conditions during decoloring and coloring are the same as in Comparative Example 2. As shown in FIG. 15, by using a material different from that of Example 1, the transmission spectrum peak wavelength when the EC element 6 is colored is around 550 nm, which is different from any of the emission spectrum peak wavelengths of the light emitting section. FIG. 16 shows the emission spectrum of Example 2 when the EC element is disposed and the light is reduced. According to FIG. 15, when the EC element 6 is decolored, the emission intensity is about 30 around 400 nm and about 18 around 650 nm. However, when the EC element 6 is colored, the emission intensity is 1 around 400 nm and around 650 nm. It turns out that it has reduced to the following. The dimming effect at this time had a high dimming rate with an emission luminance of about 5%. Further, as shown in FIG. 6, in Example 2, the variation with respect to the target value is ± 2% at the time of dimming when the target value of the emission luminance is 10%, and ± 5% at the time of dimming when the target value is 5%. Thus, the variation with respect to Comparative Example 1 could be greatly improved. It should be noted that the dimming with the target value of the emission luminance of 10% could be performed when a voltage of 2.5 V was applied to the EC element 6. As for chromaticity, a large change in chromaticity as in Comparative Example 2 is not confirmed between the target value of 100% and 5%, and white light emission is maintained, which is preferable. In addition, even when the emission spectrum peak wavelength of the light emitting part is 3 wavelengths or more, the EC element 6 having a transmission spectrum peak wavelength at the time of coloring different from any of the emission spectrum peak wavelengths of the light emitting part is applied. As a result, it is possible to obtain the same effect as in the second embodiment.

  Therefore, even if the light attenuation rate is high by dimming the organic EL panel with the EC element 6 having different emission spectrum peak wavelength of the light emitting part and transmission spectrum peak wavelength at the time of coloring as in the present invention. It is clear from FIG. 6 that it is possible to exhibit excellent dimming performance with little variation in luminance and little change in chromaticity, and to improve the merchantability as a light emitting device.

  The present invention is suitable for an organic EL panel used for a display device or a lighting device.

DESCRIPTION OF SYMBOLS 1 Support substrate 2 1st electrode 3 Functional layer 4 2nd electrode 5 Sealing substrate 6 EC element

Claims (5)

A light-emitting portion having a pair of electrodes formed on a support substrate and at least one of which is translucent and an organic light-emitting layer formed between the electrodes, and an electrochromic element disposed on the light extraction side An organic EL panel
The organic EL panel, wherein a transmission spectrum peak wavelength when a voltage is applied to the electrochromic element is different from an emission spectrum peak wavelength of the light emitting part. 2. The organic EL panel according to claim 1, wherein an emission spectrum peak wavelength of the light emitting portion is 500 nm or more and 700 nm or less, and a transmission spectrum peak wavelength when the voltage of the electrochromic device is applied is 300 nm or more and less than 500 nm. . 2. The organic EL according to claim 1, wherein an emission spectrum peak wavelength of the light emitting portion is 300 nm or more and 500 nm or less, and a transmission spectrum peak wavelength when the voltage of the electrochromic device is applied is greater than 500 nm and 700 nm or less. panel. 2. The organic EL panel according to claim 1, wherein there are a plurality of emission spectrum peak wavelengths of the light emitting portion, and a transmission spectrum peak wavelength when a voltage is applied to the electrochromic element is different from any of the emission spectrum peak wavelengths. 5. The organic material according to claim 1, wherein a difference between a transmission spectrum peak wavelength when the voltage of the electrochromic element is applied and an emission spectrum peak wavelength of the light emitting portion is 50 nm or more. 6. EL panel.

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