JP2006278035A - Light emission distribution estimation method, light emission distribution estimation device, light emission distribution estimation program, record medium, display device, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emission distribution estimation method capable of efficiently and accurately estimating light emission distribution in a luminescent layer in an organic EL element. <P>SOLUTION: An EL light emission distribution W<SB>EL</SB>(x) of a luminescent layer in the organic EL element can be estimated based on fairly reliable data, for instance, measurement data I<SB>EL</SB>(λ) of an EL spectrum, measurement data I<SB>PL</SB>(λ) of a PL spectrum, calculation data η(λ, x) of light-taking-out efficiency. Further, since no additional structure need be added to the organic EL element in estimation of the W<SB>EL</SB>(x), the W<SB>EL</SB>(x) can be efficiently estimated with an intrinsic structure of the organic EL element utilized to the full. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emission distribution estimation method, a light emission distribution estimation device, a light emission distribution estimation program, a recording medium, a display element, and an image display device.

  Conventionally, a light emitter that is excited based on an applied electric field and can emit light having a predetermined emission spectrum, a first electrode that is provided on one surface side of the light emitter and can transmit light, and the light emitter There is known a display element that includes a second electrode that is provided on the other surface side opposite to the one surface and can reflect light. As such a display element, a so-called LED (Light Emitting Diode) or the like is known, and more specifically, an organic EL (Electro Luminescence) element or an inorganic EL element is known.

FIG. 10 is a cross-sectional view schematically showing the configuration of the organic EL element.
In this figure, an organic EL element 1 includes a transparent substrate 11 made of a transparent material such as glass, a transparent anode 12 (first electrode) made of ITO (Indium tin oxide), and a hole transport layer. 13, a light emitting layer 14 (light emitter), an electron transport layer 15, and a cathode 16 (second electrode) made of metal or the like and capable of reflecting light are sequentially stacked. The anode 12 and the cathode 16 are connected to the power source 2 so that an electric field E from the anode 12 toward the cathode 16 is generated. Under such an electric field E, holes (indicated by “+” in FIG. 10) injected from the anode 12 to the hole transport layer 13 are transported to the cathode 16 side, and from the cathode 16 to the electron transport layer. Electrons injected into 15 (indicated by “−” in FIG. 10) are transported to the anode 12 side. Holes and electrons are recombined in the light emitting layer 14 to generate hole-electron pairs (hereinafter referred to as excitons) in an excited state. Thereafter, the energy of excitons is transferred to the light emitting material constituting the light emitting layer 14, and the light emitting material is excited to emit light. It is known that the emission spectrum at this time is mainly determined according to the properties of the luminescent material, and when only Alq3 is used as the luminescent material, the emission spectrum has the maximum intensity at the wavelength λ ₀ ≈530 nm. The light emitting layer 14 can be composed of only one kind of light emitting material, or can be composed of two or more kinds of materials, for example, a host material and a dopant material. The light generated in the light emitting layer 14 is emitted outside the organic EL element 1 through the transparent anode 12 and the transparent substrate 11.

In the organic EL device 1 having the configuration described above, in order to improve the display performance, amplifying the light with a peak wavelength lambda ₀ form a resonance structure for the peak wavelength lambda ₀ of the light between the anode 12 and cathode 16 The technique to do is known (for example, refer patent document 1). Specifically, the optical distance L (= Σnd: where n is the refractive index of each layer, and d is the thickness of each layer) of the layer including the anode 12, the hole transport layer 13, the light emitting layer 14, and the electron transport layer 15. And a phase shift Φ when light is reflected by the cathode 16, the organic EL element 1 is configured to satisfy the following formula (1), whereby a resonant structure can be formed.

  In order to simplify the description, a case where the cathode 16 is an ideal conductor and the electron transport layer 15 in contact with the cathode 16 is an ideal transparent body will be described below as an example. In this case, the phase shift at the cathode 16 is Φ = −π. Therefore, Formula (1) can be transformed into the following Formula (2).

  Further, when the formula (2) is modified, the following formula (3) is obtained.

Thus, it can be seen that in order to form a resonance structure for light having the peak wavelength λ ₀ , the optical distance L should be set to 1/4 times, 3/4 times,... Of the peak wavelength λ ₀ .

Figure 11 shows the standing wave peak wavelength lambda ₀ occurring in the resonant structure formed when the optical distance L is 3/4 times the peak wavelength lambda ₀ schematically. For convenience of explanation, in this figure, the hole transport layer 13, the light emitting layer 14, and the electron transport layer 15 are shown in an integrated manner. A solid line waveform represents light traveling toward the anode 12 side, and a broken line waveform represents light traveling toward the cathode 16 side. Position A spaced by optical distance lambda _0/4 from the surface of the cathode 16 has become the belly of the standing wave, position B spaced by optical distance lambda _0/2 from the surface of the cathode 16 in the section of the standing wave It has become.

In order to maximize the display performance of the organic EL element 1 using the resonance structure with respect to the light having the peak wavelength λ ₀ as described above, the light emitting layer 14 is formed so as to include the antinode position A in the standing waveform. Of course, it is particularly preferable that the maximum light emission position in the light emission distribution in the light emitting layer 14 coincides with the antinode position A in the standing waveform. Therefore, in order to improve the display performance of the organic EL element 1, information on the light emission distribution in the light emitting layer 14 is indispensable.

  As described above, the light emission in the light emitting layer 14 is caused by the generation of excitons (hole-electron pairs). Therefore, the light emission distribution in the light emitting layer 14 is the exciton distribution in the light emitting layer 14. It can also be interpreted as a generation distribution. However, the exciton generation distribution in the light emitting layer 14 (light emission distribution in the light emitting layer 14) is the work function of the anode 12, the work function of the cathode 16, and the carriers (holes) of the substances constituting the layers 13, 14, 15. Since it depends on various quantities such as electron) mobility, ionization potential and energy gap, it is very difficult to calculate by calculation. It is also difficult to directly measure the light emission distribution in the light emitting layer 14. This is because light emitted to the outside of the organic EL element 1 through the transparent anode 12 and the transparent substrate 11 is a mixed light of the light generated at each position in the light emitting layer 14, so that light is emitted even if this is measured. This is because it is difficult to obtain information about the distribution.

  Therefore, instead of directly acquiring the light emission distribution in the light emitting layer 14 by calculation or measurement, development of a technique for estimating this has been attempted. Currently, for example, the following two light emission distribution estimation methods are known. Yes.

  In the first light emission distribution estimation method, various light emission distributions such as a work function of the anode 12, a work function of the cathode 16, carrier mobility of substances constituting each layer 13, 14, 15, ionization potential, and energy gap are determined. The amount of light is measured in advance, a light emission simulation of the organic EL element 1 is performed using a physical model set based on these measured amounts, and the light emission distribution is estimated based on the simulation result.

  In the second light emission distribution estimation method (for example, see Non-Patent Document 1), as shown in FIG. 12, a dope layer 17 having a minute thickness is added to the light emitting layer 14, and the light is emitted out of the organic EL element 1. Measure the intensity of light. The measurement of the light intensity is sequentially performed a plurality of times while sequentially changing the position of the doped layer 17 in the light emitting layer 14. Based on the correlation between the position of the doped layer 17 in the light emitting layer 14 and the measured light intensity, the light emission distribution in the light emitting layer 14 (without the doped layer 17 added) is estimated. .

International Publication No. 01/039554 Pamphlet C.W.Tang, S.A.VanSlyke, and C.H.Chen, J.Appl.Phys. 65 (9), 3610, (1989)

  However, since the light emission mechanism of the light emitting layer 14 of the organic EL element 1 is not sufficiently elucidated at present, the validity of the physical model used for the light emission simulation in the first light emission distribution estimation method should be determined with sufficient accuracy. I can't. For this reason, it is impossible to accurately verify whether or not the estimated light emission distribution is correct, and there is a problem that the first light emission distribution estimation method does not ensure sufficient reliability.

  Further, in the second light emission distribution estimation method, the doped layer 17 is additionally added to the light emitting layer 14, but the substance constituting the doped layer 17 has an energy gap from the host material constituting the light emitting layer 14. In many cases, the HOMO (Highest Occupied Molecular Orbital) level and the LUMO (Lowest Unoccupied Molecular Orbital) level are present inside the corresponding levels of the host material constituting the light emitting layer 14. The doped layer 17 tends to hinder movement of holes and electrons. Therefore, in the second light emission distribution estimation method, there is a possibility that the original light emission state of the light emitting layer 14 (without the doped layer 17 added) may not be accurately reproduced, and there is a problem in estimation accuracy. Further, since the complicated operation of adding the doped layer 17 in the light emitting layer 14 has to be repeated a plurality of times while sequentially changing the position of adding the doped layer 17 in the light emitting layer 14, the work efficiency is improved. It was bad and costly.

  An object of the present invention is to provide a light emission distribution estimation method, a light emission distribution estimation apparatus, a light emission distribution estimation program, a recording medium, a display element, and an image display apparatus capable of efficiently and accurately estimating a light emission distribution in a light emitting body in a display element. Is to provide.

  The light emission distribution estimation method of the present invention includes a light emitter that is excited based on an applied electric field and can emit light having a predetermined light emission spectrum, and a first light source provided on one surface side of the light emitter that can transmit light. In a display element comprising one electrode and a second electrode provided on the other surface side opposite to the one surface of the light emitter, an electric field is applied by the first electrode and the second electrode A light emission distribution estimating method for estimating a light emission distribution in the luminous body in which an electric field is applied by the first electrode and the second electrode to excite and emit light, and the light is emitted through the first electrode. Based on the characteristics of each component of the display element based on the field excitation emission spectrum measurement process for measuring the spectrum of light (hereinafter referred to as the field excitation emission light spectrum), The ratio of the light emitted through the first electrode in the light generated in the above (hereinafter referred to as light extraction efficiency) at each position where the light is generated in the luminous body and at each position. A light extraction efficiency calculation step for calculating for each wavelength of the generated light, and a light emission distribution estimation step for estimating a light emission distribution in the luminous body based on the emission spectrum, the light extraction efficiency, and the electric field excitation emission light spectrum And is provided.

First, the meaning of terms will be described.
“Luminescence distribution” means the distribution of luminescence in the luminescent body and can be expressed as a function W _EL (x) for the position x in the luminescent body. As described above, the emission distribution W _EL (x) can also be interpreted as an exciton generation distribution in the luminous body. In order to clarify that the light emission distribution W _EL (x) is based on electric field excitation, in the following description, the light emission distribution W _EL (x) is referred to as “EL light emission distribution W _EL (x)”. Sometimes expressed.
“Emission spectrum” means the spectrum of light emitted by a light emitter and can be expressed as light intensity I _L (λ) as a function of the wavelength of light λ. As described above, the emission spectrum is determined mainly depending on the properties of the material constituting the light emitter. However, when the light emitter is composed of two or more kinds of materials, the emission spectrum changes depending on the material composition. For example, when a light emitter is formed by dispersing a dopant material in a host material, light emission from the dopant material is mainly, but the emission spectrum of the dopant material depends on the dielectric constant and density of the host material. Change. Also, the emission spectrum changes due to concentration quenching and self-absorption depending on the concentration of dopant material added.
“Light extraction efficiency” means the proportion of light emitted outside the display element through the first electrode when light of wavelength λ is generated at position x in the luminous body. It can be expressed as a function η (λ, x).
"Electric field excited emission light spectrum" means a spectrum of light emitted from the display element through the first electrode when an electric field is applied by the first electrode and the second electrode to excite and emit light. It can be expressed as light intensity I _EL (λ) as a function of light wavelength λ.
Note that the subscript “EL (Electro Luminescence)” relates to electric field excitation.

Next, the display mechanism of the display element will be described using the above terms.
First, when an electric field is applied by the first electrode and the second electrode, the light emitter emits light according to the light emission distribution W _EL (x). That is, in the position x of the light emitting body, is generated W number of excitons in accordance with the _{EL (x),} light intensity corresponding to W _{EL (x)} is generated.
At this time, the light having the intensity corresponding to W _EL (x) generated at the position x has an emission spectrum represented by the light intensity I _L (λ). It depends on the substance to be used and is independent of the position x in the luminous body). Therefore, the intensity of the light having the wavelength λ generated at the position x is determined according to the product W _EL (x) · I _L (λ).
The light (wavelength λ, generation position x) is emitted outside the display element through the first electrode in accordance with the light extraction efficiency η (λ, x). Therefore, in the light of the wavelength lambda generated at position x, the intensity of light emitted outside the display device through the first electrode, the product _{W EL (x) · I L} (λ) · η (λ, x )
If this product W _EL (x) · I _L (λ) · η (λ, x) is integrated with respect to the position x, an amount corresponding to the intensity of light of wavelength λ emitted from the display element through the first electrode is obtained. Can be calculated. This calculated amount corresponds to the light intensity I _EL (λ) of the wavelength λ in the electric field excitation emission light spectrum.
Therefore, if the normalization constant to be applied to each term is ignored, the following formula (4) is established.

As described above, the electric field excitation emission light spectrum I _EL (λ) is determined based on the three quantities of the light emission distribution W _EL (x), the light emission spectrum I _L (λ), and the light extraction efficiency η (λ, x). However, from a different viewpoint, it can be seen that the emission distribution W _EL (x) can be estimated based on the other three quantities.

According to the emission distribution estimation method of the present invention, the electric field excitation emission light spectrum I _EL (λ) is measured, and the light extraction efficiency η (λ, x) is determined based on the characteristics of each component of the display element. Since it is calculated, the light emission distribution W _EL (x) in the light emitter can be estimated based on these two quantities and the light emission spectrum I _L (λ). Note that since the emission spectrum I _L (λ) is determined according to the substance constituting the light emitter, it can be measured in advance by a test or the like for the constituent substance. Further, as will be described later, the emission spectrum I _L (λ) can be calculated based on the light excitation emission light spectrum.

In the light emission distribution estimation method of the present invention as described above, the light emission distribution W _EL (x) is estimated based on the three quantities I _EL (λ), η (λ, x), and I _L (λ). In this case, it is sufficient to perform the arithmetic processing based on the equation (4), and a light emission simulation is performed by setting a physical model that is not well established theoretically and experimentally like the conventional first light emission distribution estimation method. There is no need to do it. Therefore, according to the light emission distribution estimation method of the present invention, the light emission distribution W _EL (x) can be estimated with high accuracy based on the three quantities that are sufficiently reliable.

Further, according to the emission distribution estimation method of the present invention, the original configuration of the display element can be achieved without adding an additional configuration such as a doped layer to the light emitter as in the conventional second emission distribution estimation method. Since the light emission distribution W _EL (x) can be estimated by utilizing it, the estimation accuracy can be improved. In addition, since it is not necessary to perform a complicated operation of adding an additional structure such as a doped layer to the light emitter, the working efficiency can be improved and the working cost can be reduced.

  Further, in the emission distribution estimation method of the present invention, an excitation light that can excite and emit the illuminant is irradiated to excite and emit the illuminant, and a spectrum of light emitted through the first electrode ( And a light excitation emission light spectrum measurement step for measuring the light excitation emission light spectrum, and an emission spectrum calculation step for calculating the emission spectrum based on the light excitation emission light spectrum and the light extraction efficiency, In the emission distribution estimation step, it is preferable that the emission distribution in the luminous body is estimated based on the emission spectrum calculated in the emission spectrum calculation step, the light extraction efficiency, and the electric field excitation emission light spectrum.

Here, the “photoexcitation emission light spectrum” means a spectrum of light emitted outside the display element through the first electrode when the illuminant is excited and emitted by irradiating excitation light, and has a wavelength λ of light. It can be expressed as the light intensity I _PL (λ) as a function.
Note that the subscript “PL (Photo Luminescence)” relates to photoexcitation.

  In the case of photoexcitation, the following equation (5) similar to equation (4) in the case of electric field excitation holds.

Here, W _PL (x) means a light emission distribution in the luminous body due to photoexcitation. In order to clarify that the emission distribution W _PL (x) is based on photoexcitation, in the following description, the emission distribution W _PL (x) is referred to as “PL emission distribution W _PL (x)”. May be expressed.
The light emission distribution W _PL (x) is determined according to the intensity distribution L (x) of the excitation light in the light emitting body. In particular, when it can be assumed that the intensity distribution L (x) is substantially uniform, the emission distribution W _PL (x) is also substantially uniform. Therefore, if W _PL (x) = W _PL0 (constant) is set, equation (5) can be transformed into the following equation (6).

Then, as shown in the following equation (7), the integral value for x of the light extraction efficiency η (λ, x) is set as η ₀ (λ), and equation (6) is expressed for the emission spectrum I _L (λ). If it melts | dissolves, the following formula | equation (8) will be obtained.

As described above, in the emission spectrum calculation step, the emission spectrum I _L (λ) can be calculated based on the light excitation emission light spectrum I _PL (λ) and the light extraction efficiency η (λ, x).

According to the light emission distribution estimation method as described above, the light emission spectrum I _L (λ) can be calculated with high accuracy based on the actual light emission state of the light emitter incorporated in the display element. The estimation accuracy of _EL (x) can be improved.

  In the emission distribution estimation method of the present invention, in the emission spectrum calculation step, the intensity distribution of the excitation light in the luminous body in the light excitation emission light spectrum measurement step based on the characteristics of each component of the display element. It is preferable that the emission spectrum is calculated based on the intensity distribution, the light extraction efficiency, and the light excitation emission light spectrum.

When the assumption that the intensity distribution L (x) in the luminous body is substantially uniform does not hold, the luminous distribution W _PL (x) in the luminous body is not substantially uniform and varies.
However, the intensity distribution L (x) can be accurately calculated based on the characteristics (such as the refractive index) of each component of the display element. Therefore, the light emission distribution W _PL (x) in the light emitting body can be accurately calculated. In this case, equations (5) to (8) cannot be modified under the above assumption, but instead, equation (5) can be modified into the following equation (9).

Here, since the quantities I _PL (λ), W _PL (x), and η (λ, x) on the right side are all measured or calculated, the emission spectrum I _L (λ) is expressed by Equation (9). Can be calculated.

According to the light emission distribution estimation method as described above, the light emission spectrum I _L (λ) can be calculated with high accuracy in consideration of variations in the intensity distribution L (x) in the light emitting body. The estimation accuracy of W _EL (x) can be improved.

  In the light emission distribution estimation method of the present invention, in the light emission distribution estimation step, a light emission distribution candidate setting step for arbitrarily setting light emission distribution candidates (hereinafter referred to as light emission distribution candidates) in the light emitter, and the light emitter Is assumed to emit light based on the emission distribution candidate, the spectrum of the light emitted through the first electrode (hereinafter referred to as electric field excitation emission light spectrum candidate), the emission distribution candidate, the emission spectrum, The electric field excitation emission light spectrum candidate calculation step calculated based on the light extraction efficiency and the electric field excitation emission light spectrum candidate are compared with the electric field excitation emission light spectrum, and when the difference between the two is within a predetermined range, A spectrum comparison step for estimating the emission distribution candidate used for calculation of the electric field excitation emission light spectrum candidate as the emission distribution in the luminous body, It is preferably provided.

The EL light emission distribution candidate (EL light emission distribution W _EL (x) candidate) set in the light emission distribution candidate setting step is set as W _EL ′ (x). In the electric field excitation outgoing light spectrum candidate calculation step, electric field excitation outgoing light spectrum candidate I _EL is obtained according to the following equation (10) obtained by substituting W _EL ′ (x) into W _EL (x) in equation (4). '(Λ) is calculated.

In the spectrum comparison step, the calculated I _EL '(λ) is compared with the measured I _EL (λ), and when the difference between the two is within a predetermined range, it is used for calculating I _EL ' (λ). The estimated EL emission distribution candidate W _EL ′ (x) is estimated to be the EL emission distribution W _EL (x) in the luminous body.

According to the light emission distribution estimation method as described above, the EL light emission distribution for generating the spectrum candidate I _EL '(λ) close to the spectrum I _EL (λ) generated based on the actual EL light distribution W _EL (x). Since the candidate W _EL '(x) is estimated to be an actual EL emission distribution, the estimated EL emission distribution (candidate) W _EL ' (x) and the actual EL emission distribution W _EL (x) The difference can be suppressed within a predetermined range, and the EL emission distribution W _EL (x) can be estimated with high accuracy.

  In the emission distribution estimation method of the present invention, in the spectrum comparison step, a plurality of sample wavelengths are set, each intensity data for each sample wavelength in the field excitation emission light spectrum candidate, and the field excitation emission light spectrum. When the sum of the squares of the individual differences of the respective intensity data for each sample wavelength is equal to or less than a predetermined threshold value, the emission distribution candidate used for the calculation of the electric field excitation emission light spectrum candidate is used as the light emission in the luminous body. It is preferable to estimate the distribution.

When N sample wavelengths λi = λ1, λ2,..., ΛN (i = 1, 2,..., N) are set in the spectrum comparison step, each sample wavelength in the spectrum candidate I _EL ′ (λ) The sum of squares of the individual differences Δ of each intensity data I _EL ′ (λi) for λi and intensity data I _EL (λi) for each sample wavelength λi in the spectrum I _EL (λ)

Is calculated and compared with the threshold Δ _0, and whether or not the light emission distribution candidate W _EL '(x) used for calculating the spectrum candidate I _EL ' (λ) may be estimated as the light emission distribution W _EL (x). Determined.
When a continuous sample wavelength is set, Δ can be calculated by rewriting the right side of Equation (11) using the integration for λ.

  According to the light emission distribution estimation method as described above, the light emission distribution can be estimated with stable accuracy based on a mathematical method.

  The light emission distribution estimation device of the present invention can emit light having a predetermined emission spectrum that is excited based on an applied electric field, and can transmit light provided on one surface side of the light emitter. In a display element comprising a first electrode and a second electrode provided on the other surface side opposite to the one surface of the light emitter, an electric field is applied by the first electrode and the second electrode. A light emission distribution estimating device for estimating a light emission distribution in the light emitter in the case where an electric field is applied by the first electrode and the second electrode to excite and emit the light emitter, and the electric field An electric field excitation outgoing light spectrum measuring means for measuring a spectrum (electric field excitation outgoing light spectrum) of light emitted through the first electrode when an electric field is applied by the applying means; and the display Based on the characteristics of each component of the child, the ratio (light extraction efficiency) of the light emitted through the first electrode out of the light generated in the light emitting body is represented by each position where the light is generated in the light emitting body. And a light extraction efficiency calculating means for calculating for each wavelength of light generated at each position, and based on the emission spectrum, the light extraction efficiency, and the electric field excitation emission light spectrum, And a light emission distribution estimating means for estimating the light emission distribution.

  In the emission distribution estimation device of the present invention, excitation light irradiation means for irradiating the light emitter with excitation light capable of exciting and emitting the light to excite and emit the light emitter, and excitation by the excitation light irradiation means A light excitation emission light spectrum measuring means for measuring a spectrum (light excitation emission light spectrum) of light emitted through the first electrode during light irradiation, and the emission spectrum based on the light excitation emission light spectrum and the light extraction efficiency. An emission spectrum calculating means for calculating the emission spectrum, the emission distribution estimating means is based on the emission spectrum calculated by the emission spectrum calculating means, the light extraction efficiency, and the electric field excitation emission light spectrum. It is preferable to estimate the light emission distribution.

  In the light emission distribution estimation apparatus of the present invention, the light emission distribution estimation means includes light emission distribution candidate setting means for arbitrarily setting light emission distribution candidates (light emission distribution candidates) in the light emitter, and the light emitter is the light emission distribution. When it is assumed that light is emitted based on a candidate, a spectrum of light emitted through the first electrode (electric field excitation light spectrum candidate) is calculated based on the light emission distribution candidate, the light emission spectrum, and the light extraction efficiency. The field excitation emission light spectrum candidate calculation means and the field excitation emission light spectrum candidate are compared with the field excitation emission light spectrum, and when the difference between the two is within a predetermined range, the field excitation emission light spectrum candidate is calculated. It is preferable to include a spectrum comparison unit that estimates that the light emission distribution candidate used in step 1 is a light emission distribution in the light emitting body.

  The light emission distribution estimation apparatus of the present invention having the above-described configuration has a structure for carrying out the light emission distribution estimation method of the present invention described above, and therefore has the same functions and effects as the light emission distribution estimation method of the present invention. Can play.

  In the emission distribution estimation apparatus of the present invention, a single spectrum measuring unit capable of measuring a light spectrum is provided, and the single spectrum measuring unit functions as the electric field excitation emission light spectrum measuring unit, and It preferably functions as the light excitation emission light spectrum measurement means.

  According to the light emission distribution estimation apparatus having such a configuration, since it is sufficient to provide a single spectrum measurement means as the electric field excitation emission light spectrum measurement means and the light excitation emission light spectrum measurement means, the number of parts and parts of the light emission distribution estimation apparatus Cost can be reduced.

  Further, the emission distribution estimation program of the present invention is capable of transmitting light that is excited on the basis of an applied electric field and can emit light having a predetermined emission spectrum, and is provided on one side of the light emitter. In a display element comprising a first electrode and a second electrode provided on the other surface side opposite to the one surface of the light emitter, an electric field is applied by the first electrode and the second electrode. An emission distribution estimation program for estimating an emission distribution in the luminous body in a case where an electric field is applied by the first electrode and the second electrode to excite and emit the luminous body, and the light is emitted through the first electrode. Based on the characteristics of each component of the display element, and an electric field excitation emission light spectrum measurement step for measuring the spectrum of the emitted light (field excitation emission light spectrum) The ratio of light emitted through the first electrode (light extraction efficiency) in the light generated inside is determined for each position where light is generated in the light emitting body and the light generated at each position. A light extraction efficiency calculation step for calculating for each wavelength of light, and a light emission distribution estimation step for estimating a light emission distribution in the light emitter based on the emission spectrum, the light extraction efficiency, and the electric field excitation emission light spectrum. It is made to perform by the computer incorporated in the distribution estimation apparatus.

  The recording medium of the present invention is characterized in that the light emission distribution estimation program is recorded and can be read by a computer incorporated in the light emission distribution estimation apparatus.

  Since the emission distribution estimation program and recording medium of the present invention configured as described above are used to implement the above-described emission distribution estimation method of the present invention, the same functions and effects as the emission distribution estimation method of the present invention are described. Can be played.

In addition, the display element of the present invention is provided on the one surface side of the light emitter that is excited based on the applied electric field and can emit light having the emission spectrum with the maximum intensity at the wavelength λ ₀ . A display element comprising: a first electrode capable of transmitting light; and a second electrode provided on the other surface side opposite to the one surface of the light emitter and capable of reflecting light, The display element is configured such that a resonance structure with respect to the light having the wavelength λ ₀ is formed between the first electrode and the second electrode, and the light emission in the light emitting body estimated based on the light emission distribution estimation method. The maximum light emission position in the distribution and the position of the antinode in the standing waveform of the wavelength λ ₀ generated in the resonance structure coincide with each other.

According to the display device having such a structure, the maximum emission position of the light emission distribution of the light emitting body is, therefore coincides with the position of the antinode at the peak wavelength lambda ₀ of the standing wave resonance for light with a peak wavelength lambda ₀ structure Can be used to maximize the display performance of the display element.

  The image display device of the present invention is an image display device having a plurality of display pixels, wherein each of the display pixels is constituted by the display element.

  According to the image display device having such a configuration, since the display pixel is configured by the display element of the present invention described above, display performance can be improved.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration for carrying out a light emission distribution estimation method according to the present invention.

  The organic EL element 1 constitutes the display element of the present invention. The organic EL element 1 has the configuration shown in FIG. Here, since it becomes a repetition, description is abbreviate | omitted.

The electric field applying means 2 (corresponding to the power supply 2 in FIG. 10) excites the light emitting layer 14 by applying the electric field E to the hole transport layer 13, the light emitting layer 14, and the electron transport layer 15 by the anode 12 and the cathode 16.・ Emit light. At this time, the spectrum of light emitted from the organic EL element 1 through the anode 12 and the transparent substrate 11 is an electric field excitation emission light spectrum (hereinafter, abbreviated as EL spectrum for simplification of description) I _EL ( λ).

The excitation light irradiating means 3 includes a light source (not shown) and an optical fiber 31, and excites the light emitting layer 14 by irradiating excitation light that can excite and emit the light emitting layer 14 from the tip of the optical fiber 31.・ Emit light. At this time, the spectrum of light emitted from the organic EL element 1 through the anode 12 and the transparent substrate 11 is an optical excitation emission light spectrum (hereinafter, abbreviated as PL spectrum for simplification of description) I _PL (λ ).

  As the excitation light, for example, monochromatic light extracted by a spectroscope from the light of a lamp (for example, a xenon lamp) capable of emitting broad continuous spectrum light including the ultraviolet region and the visible region, or laser light is used. Can do.

Moreover, as a characteristic of excitation light, it is preferable that a half value width is 20 nm or less, and it is more preferable that it is 10 nm or less. This is because if the half-value width is wider than 20 nm, the overlap between the excitation light spectrum and the PL spectrum I _PL (λ) increases, which may adversely affect the estimation accuracy of the EL emission distribution W _EL (x).

  Moreover, it is preferable that excitation light has a wavelength which selectively excites and emits only the light emitting layer 14. As described above, light emission of the light-emitting layer 14 at the time of electric field excitation occurs when the light-emitting material contained in the light-emitting layer 14 is excited, so only the light-emitting material is selected in order to realize a light emission state equivalent to that at the time of electric field excitation. It is important to use excitation light having a wavelength for exciting and emitting light. Specifically, the light absorption spectrum of the light emitting material and a material other than the light emitting material (the constituent material of the hole transport layer 13 and the electron transport layer 15) is measured, and the light absorption amount of the light emitting material is large, and other than the light emitting material. The wavelength of the light absorption amount of the material may be the wavelength of the excitation light. Furthermore, when the light emitting material is composed of a host material and a dopant material added thereto, the light absorption spectrum of the host material is also measured, and the wavelength of the light absorption amount of the host material is large and the light absorption amount of the host material is small. Is preferably the wavelength of the excitation light.

The spectrum measuring means 4 is constituted by an instrument capable of measuring the intensity of light for each wavelength λ such as a spectral radiance meter or a spectrophotometer, and the EL spectrum I _EL (λ) and PL spectrum emitted from the organic EL element 1. I _PL (λ) is measured. For this reason, the spectrum measuring means 4 constitutes an electric field excitation emission light spectrum measurement means and an optical excitation emission light spectrum measurement means.

  The control unit 5 includes a light extraction efficiency calculation unit 51, an emission spectrum calculation unit 52, and an emission distribution estimation unit 53.

  The light extraction efficiency calculation means 51 is based on the characteristic of each component of the organic EL element 1 and the ratio of the light emitted through the anode 12 among the light generated in the light emitting layer 14 (light extraction efficiency η (λ, x)) is calculated for each position x where light is generated in the light emitting layer 14 and for each wavelength λ of light generated at each position x.

The emission spectrum calculating means 52 is based on the PL spectrum I _PL (λ) measured by the spectrum measuring means 4 and the light extraction efficiency η (λ, x) calculated by the light extraction efficiency calculating means 51. 14 emission spectra I _L (λ) are calculated.

The emission distribution estimating means 53 is measured by the emission spectrum I _L (λ) calculated by the emission spectrum calculating means 52, the light extraction efficiency η (λ, x) calculated by the light extraction efficiency calculating means 51, and the spectrum measuring means 4. The EL emission distribution W _EL (x) in the light emitting layer is estimated based on the EL spectrum I _EL (λ).
The light emission distribution estimation means 53 includes a light emission distribution candidate setting means 531, a field excitation emission light spectrum candidate calculation means 532, and a spectrum comparison means 533.

The light emission distribution candidate setting unit 531 arbitrarily sets an EL light emission distribution candidate (EL light emission distribution candidate W _EL ′ (x)) in the light emitting layer 14.

The field excitation emission light spectrum candidate calculation means 532 emits light from the organic EL element 1 through the anode 12 and the transparent substrate 11 when the light emitting layer 14 is assumed to emit light based on the EL light emission distribution candidate W _EL ′ (x). The light spectrum (field excitation emission light spectrum candidate (hereinafter, abbreviated as EL spectrum candidate for simplification of description) I _EL ′ (λ)) is set by the light emission distribution candidate setting means 531 Based on the EL emission distribution candidate W _EL ′ (λ), the emission spectrum I _L (λ) calculated by the emission spectrum calculation means 52, and the light extraction efficiency η (λ, x) calculated by the light extraction efficiency calculation means 51. To calculate.

Spectral comparison means 533 compares the EL spectrum candidate _{I EL} calculated by field excitation emitted light spectrum candidate calculation unit 532 '(lambda), the measured EL spectra _{I EL} by spectral measurement means 4 (lambda), both when the difference is within a predetermined range, EL spectrum candidate _{I EL '(λ) EL} emission distribution candidate _{W EL} used to calculate the' (x) a, EL light emission distribution _W EL in the light emitting layer 14 (x) It is estimated that.

In the above configuration, the electric field applying means 2, the excitation light irradiating means 3, the spectrum measuring means 4, and the control means 5 are the EL emission distribution W _EL (in the light emitting layer 14 when the electric field E is applied by the anode 12 and the cathode 16. The light emission distribution estimation apparatus which estimates x) is comprised.

Next, an estimation procedure of the EL emission distribution W _EL (x) using such an emission distribution estimation apparatus will be described with reference to the flowchart of FIG.

  In S1 (S is a process, the same applies hereinafter), the organic EL element 1 is formed.

[Electric field excitation emission spectrum measurement process]
In S <b> 2, under the control of the control unit 5, the electric field applying unit 2 applies a voltage between the anode 12 and the cathode 16 to generate an electric field E from the anode 12 toward the cathode 16. Under this electric field E, the light emitting layer 14 is excited and emits light.
In S3, under the control of the control means 5, the spectrum measurement means 4 measures the spectrum of light emitted from the organic EL element 1 (EL spectrum I _EL (λ)). The EL spectrum I _EL (λ) is normalized by its peak intensity.

[Optical excitation emission spectrum measurement process]
In S <b> 4, under the control of the control unit 5, the excitation light irradiation unit 3 irradiates the organic EL element 1 with excitation light to excite and emit the light emitting layer 14.
In S5, under the control of the control means 5, the spectrum measurement means 4 measures the spectrum of light emitted from the organic EL element 1 (PL spectrum I _PL (λ)). The PL spectrum I _PL (λ) is normalized by its peak intensity.

[Light extraction efficiency calculation process]
In S6, the characteristic of each component of the organic EL element 1 is measured. Specifically, the refractive index n and the absorption coefficient k of the material of each component are measured. Here, in particular, in order to estimate the emission distribution with high accuracy, the wavelength dispersion characteristics of the refractive index n and the absorption coefficient k are measured using a known measurement method. Here, as a known measurement method, for example, a method using an ellipsometer or a method of calculating chromatic dispersion characteristic data by fitting vertical reflection spectrum measurement data to a theoretical formula can be used. In addition, the above measurement should just be performed about each sample of each component prepared previously separately from the organic EL element 1, and it is not necessary to measure by making the organic EL element 1 itself into a measuring object.

  In S7, the light extraction efficiency calculating unit 51 calculates the light extraction efficiency η (λ, x) based on the wavelength dispersion characteristics of the refractive index n and the absorption coefficient k measured for each sample. This calculation can be performed, for example, by the following two known calculation methods.

(1) A calculation method that approximates that the light generated in the light emitting layer 14 is a plane wave and takes into account multiple reflections between the layers constituting the organic EL element 1 (plane wave approximation method)
(2) A method in which the Maxwell equation describing the propagation of electromagnetic waves (light) in a medium is differentiated in time and space, and the electromagnetic wave (light) intensity in the calculation analysis space is obtained by first-order partial differentiation (FDTD method)

Here, the plane wave approximation method (1) will be outlined. The outline of this method is as follows.
a) For light of wavelength λ, the phase film thickness δ _j of each layer (jth layer: where j = 1, 2,..., J) constituting the organic EL element 1 is calculated.
b) For the light of wavelength λ, the optical impedance Y _{j of} each layer defined by the following equation (12) is calculated for each of s-polarized light and p-polarized light.

c) For the light of wavelength λ, the characteristic matrix M _{j of} each layer defined by the following equation (13) is calculated for each of s-polarized light and p-polarized light.

d) The light of the wavelength λ generated in the light emitting layer 14 exhibits any one of the following three behaviors.
i) The light passes through the interface of the transparent substrate 11 in contact with air (the upper surface in FIG. 10) and is emitted from the organic EL element 1
ii) Reflected at the interface of the transparent substrate 11 in contact with air.
iii) Reflected on the surface of the cathode 16.
The amplitude transmittance t ₁ , amplitude reflectance r ₁ , and amplitude reflectance r ₂ corresponding to the above three behaviors i), ii), and iii) are calculated.

e) Based on the amplitude transmittance t ₁ , the amplitude reflectance r ₁ , and the amplitude reflectance r ₂ , the light emitted outside the organic EL element 1 due to multiple interference among the light generated at the position x in the light emitting layer 14. Is calculated.
f) The time average value of the pointing vector of the light with the wavelength λ generated at the position x in the light emitting layer 14 and the time average value of the pointing vector of the light emitted outside the organic EL element 1 out of this light are obtained. Then, by calculating the ratio of the two values, the light extraction efficiency η (λ, x) for the light of the wavelength λ generated at the position x is calculated.

  The pointing vector represents energy when an electromagnetic wave having an electric field vector E and a magnetic field vector H travels in the medium. When the refractive index of the medium is n, the time average value is expressed by the following equation: The amount is proportional to the square of the electric field vector E as shown in (14).

[Emission spectrum calculation step]
In S8, the emission spectrum calculating means 52 uses the PL spectrum I _PL (λ) measured in S5 and the light extraction efficiency η (λ, x) calculated in S7 to indicate the emission spectrum I of the light emitting layer 14. _L (λ) is calculated.

At this time, if the PL emission distribution in the light emitting layer 14 by photoexcitation is W _PL (x), the above equation (5) is established. The PL emission distribution W _PL (x) is determined according to the intensity distribution L (x) of the excitation light in the light emitting layer 14 in S4 and S5. Excitation light irradiated from the outside of the organic EL element 1 is multiple-reflected at the interface between the layers inside the organic EL element 1, similarly to the light generated inside the organic EL element 1. The intensity distribution L (x) of the excitation light at is not exactly uniform. However, when the optical film thickness of the light emitting layer 14 in the organic EL element 1 is sufficiently smaller than the wavelength λe of the excitation light (for example, smaller than λe × 0.2), the intensity distribution L (x ) Can be approximated as uniform. In this case, the PL emission distribution W _PL (x) can also be approximated to be uniform, so that W _PL (x) = W _PL0 (constant) and the above equation (5) is _replaced by the above equations (6), The equation (7) can be transformed into the equation (8), and the emission spectrum I _L (λ) can be calculated.

On the other hand, when the optical film thickness of the light emitting layer 14 is relatively large (for example, larger than λe × 0.2), the intensity distribution L (x) of the excitation light cannot be approximated as uniform. However, it is possible to accurately calculate the intensity distribution L (x) of the excitation light by a known calculation method such as that used in S7. In this case, the PL emission distribution W _PL (x) based on L (x) can also be accurately calculated. Therefore, the equation (5) can be transformed into the equation (9), and the emission spectrum I _L (λ) can be calculated.

[Light emission distribution candidate setting process]
In S9, the light emission distribution candidate setting unit 531 determines the EL light emission distribution candidate W _EL ′ based on a user setting operation or a light emission distribution candidate setting program stored in advance in a memory (not shown) of the control unit 5. (X) is set. The EL light emission distribution candidate W _EL ′ (x) is standardized so as to be 1 when integrated along the thickness direction of the light emitting layer 14. That is, W _EL ′ (x) is set so as to satisfy the following equation (15). In the formula (15), d is the thickness of the light emitting layer 14.

[Electric field excitation light spectrum candidate calculation process]
In S10, the field excitation emission light spectrum candidate calculation means 532 calculates the above-mentioned formula (10) based on the EL emission distribution candidate W _EL ′ (x), the emission spectrum I _L (λ), and the light extraction efficiency η (λ, x). The EL spectrum candidate I _EL ′ (λ) is calculated according to
If the average light extraction efficiency η _EL ′ (λ) for the light generated at the time of electric field excitation is defined by the following equation (16), the equation (10) can be rewritten as the following equation (17). It can be seen that the EL spectrum candidate I _EL ′ (λ) is expressed as a product of the emission spectrum I _L (λ) and the average light extraction efficiency η _EL ′ (λ).

[Spectral comparison process]
In S11, the spectrum comparison unit 533 compares the EL spectrum candidate I _EL ′ (λ) with the EL spectrum I _EL (λ), and in S12, it is determined whether or not the difference between the two is within a predetermined range.
Specifically, the spectrum comparison unit 533 sets N sample wavelengths λi = λ1, λ2,..., ΛN (i = 1, 2,..., N), and EL spectrum candidates I _EL ′. The sum of the squares of the individual differences of each intensity data I _EL ′ (λi) for each sample wavelength λi in (λ) and intensity data I _EL (λi) for each sample wavelength λi in EL spectrum I _EL (λ) calculated based on delta on the equation (11), with a predetermined threshold delta _0. When Δ ≦ Δ ₀ (determined as Yes in S12), the process proceeds to S13, where the spectrum comparison means 533 uses the EL emission used for calculating the EL spectrum candidate I _EL ′ (λ) in S10. The distribution candidate W _EL ′ (x) is estimated as the EL emission distribution W _EL (x). Further, when a Δ> Δ ₀ (it is determined No in S12), the flow returns to S9, a new EL emission distribution candidate _{W EL} '(x) is set.

<Effect of embodiment>
According to the above embodiment, the following effects can be obtained.
There is no need to perform a light emission simulation by setting a physical model that is not well established in theory and experiment as in the conventional first light emission distribution estimation method, and sufficiently reliable data (I _EL (λ), η ( EL emission distribution W _EL (x) can be estimated with high accuracy by calculation based on (λ, x), I _L (λ), etc.).

Further, without adding an additional structure such as a doped layer to the light emitting layer 14 as in the conventional second light emission distribution estimation method, the EL light emission distribution W _EL ( Since x) can be estimated, the estimation accuracy can be improved. Moreover, since it is not necessary to perform a complicated operation of adding an additional structure such as a doped layer to the light emitting layer 14, the working efficiency can be improved and the working cost can be reduced.

In addition, since the emission spectrum I _L (λ) is calculated based on the PL spectrum I _PL (λ) measured when the light emitting layer 14 is excited and emitted by the excitation light, it is incorporated into the organic EL element 1. The emission spectrum I _L (λ) can be calculated with high accuracy based on the actual light emission state of the light emitting layer 14, and the estimation accuracy of the EL emission distribution W _EL (x) can be improved.

In addition, the emission spectrum I _L (λ) can be calculated with high accuracy by taking into account variations in the intensity distribution L (x) of the excitation light in the light emitting layer 14 when measuring the PL spectrum I _PL (λ). Therefore, the estimation accuracy of the EL emission distribution W _EL (x) can be improved.

Also, an EL emission distribution candidate W _EL ′ (x) that generates an EL spectrum candidate I _EL ′ (λ) close to the EL spectrum I _EL (λ) generated based on the actual EL emission distribution W _EL (x) is obtained. Since the actual EL emission distribution W _EL (x) is estimated, the difference between the estimated EL emission distribution (candidate) W _EL ′ (x) and the actual EL emission distribution W _EL (x) is predetermined. Thus, the EL emission distribution W _EL (x) can be estimated with high accuracy.

Further, each of the intensity data I _EL ′ (λi) for each sample wavelength λi in the spectrum candidate I _EL ′ (λ) and the intensity data I _EL (λi) for each sample wavelength λi in the spectrum I _EL (λ) The EL emission distribution W _EL (x) can be estimated with stable accuracy based on a mathematical method of comparing the sum of squares of the differences Δ (equation (11)) with the threshold Δ ₀ .

In addition, since the two spectra of the EL spectrum I _EL (λ) and the PL spectrum I _PL (λ) can be measured by the single spectrum measuring means 4, the number of parts and the part cost can be reduced.

<Modification>
The present invention is not limited to the embodiment described above, and any modification of this embodiment within the scope that can achieve the object of the present invention is included in the technical scope of the present invention.

  For example, in the above-described embodiment, the organic EL element 1 is the display element for which the light emission distribution is to be estimated. However, the present invention is not limited to this. For example, the light emission distribution can be estimated for an LED such as an inorganic EL element.

  Moreover, in the said embodiment, although the cathode 16 as a 2nd electrode was comprised so that light could be reflected, you may comprise so that light can be transmitted similarly to the anode 12. FIG.

In the embodiment, the emission spectrum I _L (λ) is calculated based on the measured PL spectrum I _PL (λ). However, the emission spectrum I _L (λ) constitutes the light emitting layer 14. since dependent on the material, it is also possible to previously measure the I _{L (λ)} by such tests intended for the constituents.

In the above embodiment, the estimation method of the EL emission distribution W _EL (x) using the arbitrarily set EL emission distribution candidate W _EL ′ (x) has been described. However, the estimation method is not limited to this. . In short, any estimation method based on the emission spectrum I _L (λ), the light extraction efficiency η (λ, x), and the EL spectrum I _EL (λ) is included in the technical scope of the present invention.

In the above embodiment, Δ and Δ ₀ are compared in comparing the EL spectrum candidate I _EL ′ (λ) and the EL spectrum I _EL (λ). However, the method for comparing spectra is limited to this. Absent.

Moreover, although the said embodiment _demonstrated the estimation method of EL light emission distribution _WEL (x) in the light emitting layer 14, the light emission distribution estimation program which makes the computer perform the said estimation method, and the said light emission distribution estimation program are recorded. A computer-readable recording medium is also included in the technical scope of the present invention.

Further, the maximum light emission position in the EL light emission distribution W _EL (x) in the light emitting layer 14 estimated based on the light emission distribution estimation method described in the embodiment, the anode 12 that can transmit light, and the light can be reflected. The positions of the antinodes in the standing waveform of the peak wavelength λ ₀ generated in the resonance structure with respect to the light of the peak wavelength λ ₀ in the emission spectrum I _L (λ) of the light emitting layer 14 formed between the negative electrodes 16 coincide with each other. The display element (organic EL element 1) configured as described above is also included in the technical scope of the present invention. According to the display device having such a configuration, it is possible to maximize the display performance of the display device by using a resonant structure for the light of the peak wavelength lambda _0.

  In addition, an image display device having a display performance having a display element having such a configuration as a display pixel is also included in the technical scope of the present invention.

Next, examples of the present invention will be described.
[Device configuration]
Each component of the apparatus shown in FIG. 1 was configured using the following parts.
Electric field application means 2: Constant current generator Excitation light irradiation means 3: Monochrome light source SM-5 (manufactured by Spectrometer Co., Ltd.). This is composed of a 300 W xenon lamp, a spectroscope, and an optical fiber. Monochromatic light having a desired wavelength (excitation light: full width at half maximum 15 nm) is extracted by spectrally dividing the light of the xenon lamp with a spectroscope and irradiated at an angle of 45 ° with respect to the surface of the organic EL element 1 from the tip of the optical fiber To do.
Spectrum measuring means 4: Spectral radiance meter CS1000A (manufactured by Konica Minolta)
Control means 5: a program for calculating the light extraction efficiency η (λ, x) by the plane wave approximation method, and the EL spectrum candidate I _EL ′ (λ) and the EL spectrum I _EL (λ) are compared. Stores a program for estimating the EL emission distribution W _EL (x) according to S11 to S13

[S1: Creation of organic EL element]
ITO is formed on the glass substrate 11 by sputtering to form the anode 12, and further, NPD, Alq3, Al and the like are sequentially formed on the glass substrate 11 by vacuum deposition to form a hole transport layer 13 (NPD) and a light emitting layer. 14 (Alq3), electron transport layer 15 (Alq3), and cathode 16 (Al) are formed, and the following three organic EL elements 1 having different thicknesses of the NPD layer and the Alq3 layer are formed (hereinafter, distinguished from each other). Therefore, the three organic EL elements 1 are expressed as an element α, an element β, and an element γ, respectively). In the above description, the light-emitting layer 14 and the electron transport layer 15 are distinguished from each other. However, in the element configuration of this example, the light-emitting layer 14 and the electron transport layer 15 are formed of only Alq3. It is a layer.

(1) Element α: substrate (glass: 0.7 mm) / anode (ITO: 140 nm) / hole transport layer (NPD: 40 nm) / light emitting layer and electron transport layer (Alq3: 80 nm) / cathode (Al: 150 nm)
(2) Element β: substrate (glass: 0.7 mm) / anode (ITO: 140 nm) / hole transport layer (NPD: 60 nm) / light emitting layer and electron transport layer (Alq3: 60 nm) / cathode (Al: 150 nm)
(3) Element γ: substrate (glass: 0.7 mm) / anode (ITO: 140 nm) / hole transport layer (NPD: 80 nm) / light emitting layer and electron transport layer (Alq3: 40 nm) / cathode (Al: 150 nm)

[S2 to S3: Measurement of EL spectrum I _EL (λ)]
When an electric field E was applied between the anode 12 (ITO) and the cathode 16 (Al) by a constant current generator (electric field applying means 2) under the condition that the current density was 10 mA / cm ² , the elements α, β, γ All emitted green light. Then, this green light was measured by a spectral radiance meter (spectrum measuring means 4), and EL spectrum I _EL (λ) data was obtained for each of the elements α, β, and γ (note that I _EL (λ) Is normalized by its peak intensity). FIG. 3 shows I _EL (λ). It can be seen that the peak wavelength of the EL spectrum I _EL (λ) becomes shorter in the order of the elements α, β, γ.

[S4 to S5: Measurement of PL spectrum I _PL (λ)]
When excitation light having a wavelength of 430 nm and a full width at half maximum (see FIG. 4) is irradiated at an angle of 45 ° with respect to the surfaces of the elements α, β, and γ using the excitation light irradiation means 3, Similar to (S2 to S3), green light emission was observed. Then, this green light is measured by the same spectral radiance meter used for the measurement of the EL spectrum I _EL (λ), and the data of the PL spectrum I _PL (λ) is obtained for each of the elements α, β, and γ. (Note that I _PL (λ) is normalized by its peak intensity). FIG. 4 shows I _PL (λ). As in the EL spectrum I _EL (λ) of FIG. 3, it can be seen that the peak wavelength of the PL spectrum I _PL (λ) decreases in the order of the elements α, β, and γ.

[S6-S7: Calculation of light extraction efficiency η (λ, x)]
On a glass substrate, ITO (140 nm) of anode 12 material, NPD (40 nm) of hole transport layer 13 material, Alq3 (40 nm) of light emitting layer 14 and electron transport layer 15 material, Al (10 nm) of cathode 16 material Thin films were prepared respectively. And the refractive index n and the absorption coefficient k of each thin film were measured using optical refractive index measuring apparatus FilmTEK3000 (made by SCI). Using the measured refractive index n and absorption coefficient k, the light extraction efficiency η (λ, x) was calculated by the plane wave approximation method. 5, 6 and 7 show the light extraction efficiencies η (λ, x) of the elements α, β and γ, respectively. The data of A, B, C, D, and E in these drawings represent the light extraction efficiency on each surface when the Alq3 layer constituting the light emitting layer 14 is divided into five equal parts.

[S8: Calculation of emission spectrum I _L (λ)]
Based on the PL spectrum I _PL (λ) in FIG. 4 and the light extraction efficiency η (λ, x) in FIGS. 5 to 7, the emission spectrum I _L (λ) is calculated for each of the elements α, β, and γ. did. FIG. 8 shows the calculated emission spectrum I _L (λ). It can be seen that the elements α, β, and γ have the same peak wavelength. This is because, as described above, the peak wavelength of the emission spectrum I _L (λ) is determined according to the substance constituting the light emitting layer 14 and is independent of the thickness of the light emitting layer 14 and the like. Conversely, from the calculation data of FIG. 8, it can be seen that the measured PL spectrum I _PL (λ) of FIG. 4 is emitted from the same substance (Alq3).

[S9 to S13: Estimation of EL Emission Distribution W _EL (x)]
The EL emission distribution W _EL (x) was estimated based on the measurement data and calculation data acquired in the above steps. FIG. 9 shows the estimation result of the EL emission distribution W _EL (x) for each of the elements α, β, and γ. The horizontal axis of this figure represents the distance (unit: nm) from the surface of the ITO layer as the anode 12 (surface in contact with the hole transport layer 13). In addition, each position of A, B, and C in this figure represents each position of the boundary surface between the hole transport layer 13 (NPD) and the light emitting layer 14 (Alq3) in the elements α, β, and γ, respectively. Yes. From this estimation result, when the film thickness of Alq3 constituting the light emitting layer 14 is 80 nm (element α), the EL light emission distribution W _EL (x) extends over a width of 20 nm or more, and the film thickness of Alq3 becomes smaller. the width of the (element α → element β → element γ) EL emission distribution _W EL (x) is gradually narrowed, when the film thickness of the Alq3 is 40nm (element γ), the width of the EL emission distribution _W EL (x) Was found to be about 15 nm.

  The present invention can be used for estimating a light emission distribution in a light emitting body of a self-luminous display element.

It is a block diagram which shows the structure for implementing the light emission distribution estimation method which concerns on this invention. It is a flowchart which shows the estimation procedure of EL light emission distribution _WEL (x). It is a figure which shows the measurement data of EL spectrum _IEL ((lambda)) about each of organic EL element (alpha), (beta), and (gamma). It is a figure which shows the measurement data of PL spectrum _IPL ((lambda)) about each of organic EL element (alpha), (beta), and (gamma). It is a figure which shows light extraction efficiency (eta) ((lambda), x) of the organic EL element (alpha). It is a figure which shows light extraction efficiency (eta) ((lambda), x) of the organic EL element (beta). It is a figure which shows light extraction efficiency (eta) ((lambda), x) of the organic EL element (gamma). It is a figure which shows the calculation data of the emission spectrum _IL ((lambda)) about each of organic EL element (alpha), (beta), and (gamma). It is a figure which shows the estimation result of EL light emission distribution _WEL (x) about each of organic EL element (alpha), (beta), (gamma). It is sectional drawing which shows the structure of an organic EL element typically. It is sectional drawing which shows typically the standing waveform which arises in the resonance structure of an organic EL element. It is sectional drawing which shows typically the structure for implementing the conventional light emission distribution estimation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Organic EL element 2 ... Electric field application means 3 ... Excitation light irradiation means 4 ... Spectrum measurement means 5 ... Control means 11 ... Transparent substrate 12 ... Anode 13 ... Hole transport layer 14 ... Light emitting layer 15 ... Electron transport layer 16 ... Cathode DESCRIPTION OF SYMBOLS 51 ... Light extraction efficiency calculation means 52 ... Emission spectrum calculation means 53 ... Emission distribution estimation means 531 ... Emission distribution candidate setting means 532 ... Electric field excitation emission light spectrum candidate calculation means 533 ... Spectrum comparison means

Claims (12)

A light emitter that is excited based on an applied electric field and can emit light having a predetermined emission spectrum; a first electrode that is provided on one surface side of the light emitter and is capable of transmitting light; and the light emitter in the light emitter. In a display device comprising a second electrode provided on the other surface side opposite to one surface, the light emission distribution in the light emitting body is estimated when an electric field is applied by the first electrode and the second electrode. A method for estimating a light emission distribution,
An electric field for measuring a spectrum of light emitted through the first electrode (hereinafter referred to as an electric field excitation emission light spectrum) by applying an electric field by the first electrode and the second electrode to excite and emit the light emitter. Excitation emission light spectrum measurement step;
Based on the characteristics of each component of the display element, the ratio of the light emitted through the first electrode out of the light generated in the light emitter (hereinafter referred to as light extraction efficiency) is the light in the light emitter. A light extraction efficiency calculating step for calculating for each position where is generated and for each wavelength of light generated at each position;
A light emission distribution estimating step of estimating a light emission distribution in the light emitter based on the light emission spectrum, the light extraction efficiency, and the electric field excitation emission light spectrum;
A light emission distribution estimation method characterized by comprising: In the light emission distribution estimation method of Claim 1,
Irradiating excitation light that can excite and emit the illuminant to excite and emit the illuminant, and measure the spectrum of light emitted through the first electrode (hereinafter referred to as photoexcitation emission light spectrum). A photo-excited emission light spectrum measuring step,
An emission spectrum calculation step of calculating the emission spectrum based on the light excitation emission light spectrum and the light extraction efficiency;
Is provided,
In the emission distribution estimation step, the emission distribution in the luminous body is estimated based on the emission spectrum calculated in the emission spectrum calculation step, the light extraction efficiency, and the electric field excitation emission light spectrum.
A method for estimating a light emission distribution. In the light emission distribution estimation method according to claim 2,
In the emission spectrum calculation step, the intensity distribution of the excitation light in the light emitter in the light excitation emission light spectrum measurement step is calculated based on the characteristics of each component of the display element, and the intensity distribution, the light extraction Calculating the emission spectrum based on the efficiency, the light excitation emission light spectrum,
A method for estimating a light emission distribution. In the light emission distribution estimation method in any one of Claims 1-3,
In the emission distribution estimation step,
A light emission distribution candidate setting step for arbitrarily setting light emission distribution candidates in the light emitting body (hereinafter referred to as light emission distribution candidates);
When it is assumed that the illuminant emits light based on the light emission distribution candidate, a spectrum of light emitted through the first electrode (hereinafter referred to as a field-excitation light spectrum candidate) is represented as the light emission distribution candidate, the light emission. Spectrum, an electric field excitation emission light spectrum candidate calculation step for calculating based on the light extraction efficiency, and
The electric field excitation emission light spectrum candidate is compared with the electric field excitation emission light spectrum, and when the difference between the two is within a predetermined range, the emission distribution candidate used for calculation of the electric field excitation emission light spectrum candidate is A spectral comparison step for estimating the emission distribution in the luminous body;
A light emission distribution estimation method characterized by comprising: In the luminescence distribution estimation method according to claim 4,
In the spectrum comparison step, a plurality of sample wavelengths are set, each intensity data for each sample wavelength in the field excitation emission light spectrum candidate, and each intensity data for each sample wavelength in the field excitation emission light spectrum, When the sum of the squares of the individual differences is equal to or less than a predetermined threshold, the emission distribution candidate used for calculation of the electric field excitation emission light spectrum candidate is estimated to be the emission distribution in the light emitting body.
A method for estimating a light emission distribution. A light emitter that is excited based on an applied electric field and can emit light having a predetermined emission spectrum; a first electrode that is provided on one surface side of the light emitter and is capable of transmitting light; and the light emitter in the light emitter. In a display device comprising a second electrode provided on the other surface side opposite to one surface, the light emission distribution in the light emitting body is estimated when an electric field is applied by the first electrode and the second electrode. A luminescence distribution estimating device that
An electric field applying means for exciting and emitting the light emitter by applying an electric field by the first electrode and the second electrode;
Electric field excitation outgoing light spectrum measuring means for measuring a spectrum (electric field excitation outgoing light spectrum) of light emitted through the first electrode when an electric field is applied by the electric field applying means;
Based on the characteristics of each component of the display element, the ratio of the light emitted through the first electrode (light extraction efficiency) out of the light generated in the light emitter is generated in the light emitter. Light extraction efficiency calculating means for calculating each position and for each wavelength of light generated at each position;
An emission distribution estimating means for estimating an emission distribution in the luminous body based on the emission spectrum, the light extraction efficiency, and the electric field excitation emission light spectrum;
A light emission distribution estimation device comprising: In the luminescence distribution estimation apparatus according to claim 6,
Excitation light irradiating means for irradiating the illuminant with excitation light that can excite and emit light to excite and emit the illuminant;
Photoexcitation outgoing light spectrum measuring means for measuring a spectrum of light emitted through the first electrode (photoexcitation outgoing light spectrum) at the time of excitation light irradiation by the excitation light irradiation means;
An emission spectrum calculating means for calculating the emission spectrum based on the light excitation emission light spectrum and the light extraction efficiency;
Is provided,
The emission distribution estimation means estimates the emission distribution in the luminous body based on the emission spectrum calculated by the emission spectrum calculation means, the light extraction efficiency, and the electric field excitation emission light spectrum,
A light emission distribution estimation device characterized by the above. In the luminescence distribution estimation apparatus according to claim 7,
A single spectrum measuring means capable of measuring the spectrum of light is provided;
The single spectrum measurement means functions as the electric field excitation emission light spectrum measurement means, and functions as the light excitation emission light spectrum measurement means.
A light emission distribution estimation device characterized by the above. A light emitter that is excited based on an applied electric field and can emit light having a predetermined emission spectrum; a first electrode that is provided on one surface side of the light emitter and is capable of transmitting light; and the light emitter in the light emitter. In a display device comprising a second electrode provided on the other surface side opposite to one surface, the light emission distribution in the light emitting body is estimated when an electric field is applied by the first electrode and the second electrode. A luminescence distribution estimation program that
An electric field excitation emission light spectrum for measuring a spectrum of light emitted through the first electrode (electric field excitation emission light spectrum) by applying an electric field by the first electrode and the second electrode to excite and emit the light emitter. Measuring process;
Based on the characteristics of each component of the display element, the ratio of the light emitted through the first electrode (light extraction efficiency) out of the light generated in the light emitter is generated in the light emitter. A light extraction efficiency calculation step for calculating for each position and for each wavelength of light generated at each position;
A light emission distribution estimating step of estimating a light emission distribution in the light emitter based on the light emission spectrum, the light extraction efficiency, and the electric field excitation emission light spectrum;
Is executed by a computer incorporated in the luminescence distribution estimation device,
Emission distribution estimation program characterized by the above. The luminescence distribution estimation program according to claim 9 is recorded and readable by a computer incorporated in the luminescence distribution estimation apparatus.
A recording medium characterized by the above. A light emitter that is excited based on an applied electric field and can emit light having an emission spectrum with a maximum intensity at a wavelength λ ₀ , and a first electrode that is provided on one surface side of the light emitter and can transmit light A second electrode provided on the other surface side opposite to the one surface of the light emitter and capable of reflecting light, and a display element comprising:
The display element is configured such that a resonant structure with respect to light having the wavelength λ ₀ is formed between the first electrode and the second electrode,
The maximum light emission position in the light emission distribution in the luminous body estimated based on the light emission distribution estimation method according to any one of claims 1 to 5, and an antinode in the standing waveform of the wavelength λ ₀ generated in the resonance structure And the position of
A display element characterized by the above. An image display device having a plurality of display pixels,
The individual display pixels are constituted by the display element according to claim 11.
An image display device characterized by that.

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