TWI652843B - Organic electronic device manufacturing method, method for tuning color cavity of color OLED display, and inkjet printer - Google Patents

Abstract

The invention discloses a method for manufacturing an organic electronic device, which comprises: providing a substrate having at least two sets of material deposition areas, a first set of areas for a first set of elements of the device and a second set of areas for A second set of elements of the device, wherein the first set of regions and the second set of regions have different first target thicknesses and second target thicknesses of different materials to be deposited; providing the first set of regions to be deposited And at least one solution of the material on the second group of regions; and inkjet printing the solutions of the material onto the first group of material deposition regions and the second group of material deposition regions; wherein the inkjet printing includes: using A printing head including one of a plurality of nozzles to deposit the at least one solution of material, a first subset of the nozzles is used for deposition onto the first group of regions, and a second subset of the nozzles is used for Deposition onto the second group of regions; and driving the first group of nozzles with a first driving waveform and driving the second group of nozzles with a second different driving waveform to deposit different first target thicknesses And the material of the second target thickness.

Description

Organic electronic device manufacturing method, method for tuning color cavity of color OLED display, and inkjet printer

The present invention relates to technology for manufacturing organic electronic devices, specifically OLED devices such as polymer OLED (organic light emitting diode) displays.

FIG. 1a shows a section through a typical OLED device 10. This typical OLED device 10 includes a substrate 12 carrying a transparent conductive oxide layer 14 (usually ITO (Indium Tin Oxide)), which can be patterned, usually about 40 nm thick. The system deposited above this substrate typically includes a hole injection layer (HIL) 16 which is a conductive polymer such as PSS: PEDOT (polyethylenestyrenesulfonate doped polystyrenesulfonate). This hole injection layer helps match the hole energy level of the ITO anode and the light emitting polymer (and can also help to planarize ITO), and is usually about 30 nm thick, but may be as high as about 150 nm. A similar layer is usually present in an organic photovoltaic device to facilitate the extraction of holes. Commercial hole injection materials are commercially available from Plextronics in particular.

In this example, the hole injection layer is then followed by an intermediate polymer layer (interlayer (IL)) 18, also known as a hole transport layer (HTL). This intermediate polymer layer is made of a hole-transporting material that allows efficient transmission of holes; it usually has a thickness in the range of 20 nm to 60 nm and is deposited over the hole injection layer and is generally cross-linked. An exemplary material that can be used to make the interlayer is one of the polyfluorene triarylamine copolymers or the like (by Bradley et al. In Adv. Mater. Vol. 11, pages 241 to 246 (1999) and Chapter 2 describes other examples of suitable materials-see below).

One or more light-emitting polymer (LEP) layers 20 are deposited over this interlayer to form a LEP layer or stack; one typical example of a light-emitting polymer is PPV (poly (p-phenylene vinylene)). A cathode 22 is deposited over the LEP stack, for example, including a layer of sodium fluoride (NaF) followed by a layer of aluminum. An additional electron transport layer is optionally deposited between the LEP stack 20 and the cathode 22.

The device illustrated in FIG. 1a is a bottom-emitting device, that is, the light generated in the LEP stack is coupled to the outside of the device through the substrate through the transparent ITO anode layer. It is also possible to use a thin cathode layer (eg, less than about 100 nm thick) to manufacture the top-emitting device. Although the structure of FIG. 1a shows a LEP stack, the same basic structure can also be used for small molecule (and dendrimer) devices.

Those skilled in the art should understand that there are many variations of the manufacturing process of an organic electronic device, and the technology that I have described can be used in the context of the manufacturing process. For example, the ITO layer can be omitted and the hole injection layer 16 can be used as the anode layer instead. Additionally or alternatively, the conductivity of the hole injection layer 16 may be supported by an underlying metal grid (which may be transparent by using fine grid lines and / or thin metal as appropriate). This method can be used, for example, in an OLED lighting block with a large coverage area and connections at the edges. As appropriate, a flexible substrate such as PET (polyethylene terephthalate) or polycarbonate may be used.

A similar basic structure can be used for other molecular organic diodes, for example for an organic photovoltaic device.

FIG. 1b shows a top view of a portion of an exemplary three-color active matrix pixelated OLED display 200 after one of the active color layers is deposited. The figure shows an array of banks 112 and wells 114 that define the pixels of the display. In a color display, different color (sub) pixels may include green, red, and blue light emitting polymer layers, respectively.

Organic electronic devices offer many potential advantages including cheap, low temperature, and large-scale manufacturing of various substrates, including glass and plastic. Organic light-emitting diode displays offer additional advantages over other display technologies. In particular, they are bright, colorful, and fast Quick conversion and provide a wide viewing angle. Depending on the materials used, OLED devices (here including organometallic devices and devices with one or more phosphors) can be manufactured using polymers or small molecules in various colors and in multi-color displays. For general background information, refer to (for example) WO90 / 13148, WO95 / 06400, WO99 / 48160 and US4,539,570 and by Zhigang Li and Hong Meng (CRC Press (2007), ISBN 10: 1-57444-574X) Edited "Organic Light Emitting Materials and Devices", which describes several materials and devices (both small molecules and polymers). ("Small molecule" here refers to a non-polymeric small molecule-some so-called small molecules such as dendritic polymer ends can be relatively large, but have the characteristic that they do not include multiple repeating units assembled by polymerization feature).

The materials used to make an OLED or other organic electronic device can be deposited by inkjet printing. Figures 2a and 2b are taken from EP 1,219,980 and show an inkjet printing apparatus for depositing red, green and blue color filters of an electroluminescent display, but illustrate the general principles. Figures 2a and 2b show "landscape" printing; Figure 2c shows an example of an alternative print head orientation.

Thus, FIG. 2a shows an inkjet printer 200 including a base 209 which supports a first for moving a substrate 212 and an inkjet print head 222 relative to each other along two orthogonal axes Y and X The linear positioner 206 and the second linear positioner 208. The positioner 206 includes a pair of rails 254 equipped with a slide 256 supporting a turntable 251 of a table or bed 249, and the base plate 212 is supported on the table or bed. The base plate 212 is aligned on the table or bed 249 by means of the two edges of the base plate abutting against the stopper 250 thereof. The turntable 251 allows some limited rotation of the table 249 and substrate 212 relative to the print head 222 for alignment purposes (but can provide full rotation capability if needed).

The positioner 208 includes a pair of rails 252 mounted with a slider 253 that carries a rotation positioner 244, 246, 247 that allows one print head unit 226, which is one of the print heads, to independently rotate about three orthogonal axes. The print head has a rotation of about 90 degrees and the movement controlled by a small number of screws Motion is available on the other two axes (eg, to allow the nozzle plate to be aligned parallel to the substrate). Another linear positioner 248 is also mounted on the slider 253 to allow the print head unit and the print head to translate in the Z direction (ie, toward and away from the substrate 212).

A computer terminal 202 controls the inkjet printer system 200 via an umbilical 204. Terminal 202 may include a general-purpose computer with interface hardware that interfaces to the linear and rotary positioners to operate the operating system, user interface, and other inkjet printer drive and control software in a conventional manner. Therefore, the terminal 202 usually includes a data input device (such as a network interface of a floppy disk drive for receiving data defining a pattern to be printed) and a software for controlling the printer to print a data according to the stored or input data Graphic printer control software. Generally, other conventional functions such as test functions and head cleaning functions are also provided by software running on the terminal 202.

Figure 2b shows an example print head 222 in more detail. The print head has a plurality of nozzles 227, usually an orifice in a nozzle plate for ejecting fluid droplets from the print head onto the substrate. A fluid supply for printing (not shown in FIG. 2b) may be provided by the print head or a reservoir in the print head unit or may be supplied from an external source. In the illustrated example, the print head 222 has a single row 228 of nozzles 227, but in other examples of the print head, more than one row of nozzles may be provided (where the nozzles are offset along one or two dimensions). The diameter of the orifice of the nozzle 227 is usually between 10 μm and 100 μm , and the droplet size is similar. The spacing or spacing between adjacent nozzle orifices is usually between 50 μm and 1000 μm .

In general, the volume distribution of droplets is non-uniform (increasing or decreasing at the nozzles at the edge of the print head (ie, near the end of a row of nozzles)) and further non-uniformity is driven by the elements within the print head Resulting from changes in efficiency. However, when depositing materials for molecular electronic devices such as OLEDs, high resolution (usually better than the resolution required for the best high-resolution graphics) and accurate control of ink droplet volume are required Both the precise control of the volume of the deposited material (for example to control brightness / driving current / life).

One known strategy to more precisely control the volume of deposited material is to use multiple The continuous deposition of droplets instead of a single droplet covers a pixel or fills a well. However, this strategy has shortcomings and therefore we have previously described alternative techniques to achieve a uniform droplet volume to within 1% (My WO2004 / 049466). However, these techniques do not solve the problem of manufacturing, for example, a color OLED display (where LEP and HIL define a cavity and where the cavity thickness needs to be tuned to optimize the optical output from an OLED pixel).

In principle, three different printings on the same panel can be used to make a color display. However, this tripled the processing time and also started to introduce uniformity issues, because the first printing began to dry in a relatively uncontrolled manner in the printer cabinet before the third printing and the final printing were completed . Each of these three prints can be dried independently, but this will further increase the processing time.

Therefore, we will describe techniques that solve these problems and are also more widely applied to the manufacture of molecular electronic devices, such as OLED displays and organic photovoltaic devices.

According to the present invention, there is therefore provided a method of manufacturing an organic electronic device, the method comprising: providing a substrate having at least two sets of material deposition areas, a first set of areas for a first set of elements of the device and a second The group area is used for a second group element of the device, wherein the first group material deposition area and the second group material deposition area have different respective first target thicknesses and Two target thicknesses; providing at least one solution of materials to be deposited on the first group of regions and the second group of regions; and inkjet printing the solutions of materials to the first group of material deposition regions and the second group On the material deposition area; wherein the inkjet printing includes: using a print head including a plurality of nozzles to deposit the at least one solution of the material, a first subset of the nozzles is used for deposition onto the first group of areas , And a second subset of the nozzles is used for deposition onto the second group of regions; and a first driving waveform is used to drive the first group of nozzles, and a second different driving waveform is used to Moving the second set of nozzles, for respective materials different from those deposited thickness of the first target and the second target thickness.

Embodiments of these techniques facilitate accurate tuning of the volume of individual nozzles in a single print head to allow, for example, a single pass printing of a hole injection layer or interlayer with a fixed number of droplets and different target thicknesses. As explained later, in a particularly useful case, an embodiment of the method facilitates single-pass printing of three different volumes in a repeating pattern across the entire print head to manufacture a color OLED display. Therefore, embodiments of the method I have described facilitate cavity tuning of the HIL and / or interlayer adjacent (below) the LEP color layer. This can substantially substantially improve the processing time, because in the embodiment, the substrate only needs to pass under the HIL / IL (interlayer) print head once to achieve the desired HIL thickness. It is allowed to use one fixed number of droplets per printing position or one well to print different droplet volumes simultaneously (ie within a single channel), avoiding many processing problems that inkjet printing tools may encounter in other ways.

In an embodiment, the same material from all the nozzles is printed, such as the material used for one HIL and / or IL of an OLED, but in principle technology can be used to print different materials from different groups or subsets of nozzles, for example Different nozzles are in fluid communication with different "ink" reservoirs (ie different solutions of materials to be deposited). (Those skilled in the art should understand that this configuration may or may not match a group of nozzles for electrical driving or other purposes).

As previously mentioned, in the preferred embodiment, inkjet printing is printed in the strip area and the target thickness of material is deposited in a single strip area. Preferably, the same number of solution droplets from the nozzles in each subset of nozzles are deposited onto the respective deposition areas. This avoids printing a different number of droplets in each area (which would have to print droplets quickly (and then even the volume of material deposited by the droplet size "quantization") and because this would require a fixed head movement speed Under the circumstances (this is often the case), it is difficult to change the frequency of droplet deposition. For example, a low volume pixel may only require 3 droplets and a higher volume pixel may require 10 droplets, but the 3 droplet pixel is generally at the same pitch (space) as the 10 droplet pixel, making it difficult to uniform Fill 3 droplet pixels. Thus, in certain preferred embodiments, a single droplet from each nozzle in a subset of nozzles is deposited at each printing location. (Here a printing position can be defined as a "vertical" printing position, where "vertical "Straight" is perpendicular to one direction of strip area / head movement). As those skilled in the art should understand, even if only a single droplet is deposited in each printing position, there may be more than one length along the length of a region or well into which the material is deposited when manufacturing an OLED pixel Droplets.

In an embodiment of the method, the driving waveform includes pulses of different respective durations, and a longer duration is used for a larger target thickness of the deposited material. In particular, in the case of using a piezoelectric drive head, the pulse duration corresponds in a sense to the duration of the nozzle's "gate" opening, and one of the voltage steps (up or down) in the pulse corresponds It is used to give the "kickback" degree of piezoelectric materials. We have found that it is better to use the duration of a pulse for coarse control of the volume / thickness of the deposited material and then change one or more voltage steps for fine adjustment. Therefore, it is not necessarily the case that a larger target thickness of the deposited material will use a larger voltage step. In some preferred embodiments of the method, to achieve precise control of the deposited material, individual waveforms are defined for individual nozzles of the print head.

Therefore, the preferred embodiment of the method includes a collimation stage, collimating the individual nozzles of the print head with the duration (of a pulse-type driving waveform) and the size or parameters of the voltage step to determine whether to adopt for each specific nozzle The pulse duration is combined with one of the voltage steps.

In one method, this collimation is performed by determining the target thickness of the material from that particular nozzle to be deposited during the manufacture of the organic electronic device, and then varying the pulse duration / voltage (eg, repeatedly) to achieve this goal thickness. For example, the material can be deposited and then, for example, a white light interferometer (such as a Zygo New View 5000 series instrument) is used to measure the deposited thickness by interferometry. In another method, it may be better to systematically vary the pulse duration and / or voltage step and identify one of the best parameters of the measured thickness of the deposited material against one or both of these parameters. Curve or surface. Then, the desired pulse duration / voltage can be interpolated or extrapolated from this curve / surface.

Preferably, collimating a nozzle at the same time will drive the print head when manufacturing the actual device The other nozzles drive the other nozzles in substantially the same manner, for example, where the head rotates to the same pitch and the driving pulse is applied at substantially the same timing as that used when manufacturing a device. This is because crosstalk in the piezoelectric material in one nozzle can cause the activation of one nozzle to affect the behavior of the other nozzle.

Embodiments of the method also include storing data defining drive waveforms for nozzles on a non-volatile storage medium for controlling the print head of an inkjet printer.

The above technology can be used to manufacture any type of molecular (specifically, organic) electronic device. However, they are particularly useful for manufacturing organic optoelectronic devices, such as an organic light-emitting diode or an organic photovoltaic diode. Therefore, in an embodiment, each group of regions defines a separate group of color OLED sub-pixels (where a sub-pixel is one of a plurality of different color pixels of a pixel of a color OLED display), each sub-pixel It has a different target optical cavity length corresponding to a different respective color. The target thickness of the material is determined according to the length of the target cavity, and the target optical cavity length is defined by a combination of the thickness of the light emitting layer of each OLED and the thickness of the hole injection layer. Therefore, the method can be used to deposit one or both of these layers.

Those skilled in the art should understand that in the case of a three-color display, the above technique can be extended to use three subsets of nozzles with different respective drive waveforms for depositing materials of three different target thicknesses. Similarly, if desired, the technology can be extended to four or more colors.

In a related aspect, the present invention also provides the aforementioned non-volatile storage medium and an inkjet printer programmed to implement the aforementioned method (specifically, including stored data for performing the method).

10‧‧‧Typical organic light-emitting diode device

12‧‧‧ substrate

14‧‧‧Transparent conductive oxide layer / Anode metal

16‧‧‧hole injection layer

18‧‧‧Intermediate polymer layer / interlayer

20‧‧‧luminescent polymer layer

22‧‧‧Cathode

112‧‧‧Embankment / Round Embankment

114‧‧‧well

116‧‧‧Insulating material layer

118‧‧‧Cathode metal

200‧‧‧Exemplary three-color active matrix pixelated organic light-emitting diode display / inkjet printer / inkjet printer system

202‧‧‧Computer terminal / terminal

204‧‧‧Umbilical cord

206‧‧‧First linear positioner / positioner

208‧‧‧Second linear positioner / positioner

209‧‧‧Dock

212‧‧‧ substrate

222‧‧‧Inkjet print head / print head / sweep head

226‧‧‧Print head unit

227‧‧‧ nozzle

228‧‧‧Single row

244‧‧‧Rotary positioner

246‧‧‧Rotary positioner

247‧‧‧Rotary positioner

248‧‧‧Linear positioner

249‧‧‧ table or bed

250‧‧‧stop

251‧‧‧Turntable

252‧‧‧ Orbit

253‧‧‧slide

254‧‧‧ Orbit

256‧‧‧slide

510‧‧‧Short pulse width

520‧‧‧Long pulse width

710‧‧‧ droplet splitting pulse

720‧‧‧Overshoot

B‧‧‧Blue

G‧‧‧green

R‧‧‧Red

V1‧‧‧Initial voltage level / first value / starting voltage

V2‧‧‧Voltage

V3‧‧‧ third value

X‧‧‧axis / direction

Y‧‧‧axis / direction

Z‧‧‧ direction

These and other aspects of the present invention will now be further explained by way of examples only with reference to the drawings, in which: FIGS. 1a and 1b show a first example and a section through a cross section of an OLED structure, respectively. A top view of one part of a three-color pixelated OLED display; Figures 2a to 2c show an example of an inkjet printer and an example of an inkjet printer head according to the prior art, and an alternative printhead, respectively An example of orientation; Figures 3a to 3d show an example of a ring-shaped bank structure of a color OLED display and droplet-based deposition of dissolved molecular electronic materials into a well formed by these structures, and a vertical section A side view and perspective view of a well of a passive rectangular OLED display; FIG. 4 illustrates examples of different droplet sizes employed for red, green, and blue in the method according to an embodiment of the present invention; FIG. 5 shows A typical print head drive waveform; Figure 6 schematically shows the short pulse width and long pulse width and the corresponding droplet volume generated by the nozzle of the print head; and Figures 7a and 7b respectively show the measured droplet volume versus a print An exemplary mapping of the driving voltage (pulse step) of the first set of nozzles, and further exemplary driving waveforms that can be employed in an embodiment of a method according to the invention.

Examples of printers we use for OLED manufacturing are Litrex 1408, Litrex 142, and Litrex 140P printers with a Dimatix SX3 inkjet print head (from Fujifilm Dimatix Corporation). Generally, the print head prints continuous strip areas (for example, along the Y direction), and the continuous strip areas are stepped in the X direction between each strip area. The printing head can be positioned at an angle Φ to the X direction according to the actual situation, so as to reduce the dot pitch by cosΦ times.

Figure 3a shows a sweep head 222 passing over a number of pixels in a part of a color OLED display. The figure graphically shows the deposited droplets within a "water polo" type annular bank 112. In the figure, the red (R), green (G) and blue (B) sub-pixels each have a separate well (where the anode metal 14 is at the pedestal). By way of example only, in a small flat panel display, a pixel may have a width of 50 μm and a length of 150 μm to 250 μm Degree, where the bank width is (for example) 10 μm or 20 μm; in a larger display that is more suitable for applications such as a color TV, the width of one pixel can be about 200 μm. In the embodiments of the present invention, the volume of the deposited ink can be substantially substantially increased without any significant change in pixel pitch (bank size).

FIG. 3 b illustrates a configuration in which annular banks 112 define longitudinal channels each holding material for a plurality of color sub-pixels, which are themselves defined by anode metal 14. In an embodiment, the anode island may be separated by an underlying passivation layer such as silicon oxide or nitride or SOG (spin on glass). In the embodiments of FIGS. 3a and 3b, one pixel does not share any part of the ring-shaped bank with another pixel.

Figure 3c shows a section through a portion of a display such as a passive matrix OLED display (where an insulating material layer 116 is provided over a portion of the anode metal to insulate the anode metal from the cathode material deposited later). This is more clearly seen in FIG. 3d, where the insulating material layer insulates the cathode metal 118 (to provide an electrode at right angles to the anode metal electrode). The insulator may include oxide, nitride or SOG or a resist material.

Figure 3c also illustrates that when a droplet is deposited for the first time, the volume of the droplet is much larger than the volume of the well, but it dries to leave a thin layer of previously dissolved material across the bottom of the well. For example, the depth of a well may be about 1 μm, the thickness of the dried deposited material may be about 0.1 μm, and the initial height of the droplets may be about 10 μm.

Within a P-OLED device, it is desirable to have discrete HIL thickness for each different LEP color. Generally, a relatively thin HIL is preferred for best blue performance, and a particularly thick layer is preferred for red. In summary, the combination of LEP and HIL defines a cavity, and the optical output from the OLED varies sinusoidally with the cavity thickness (depth), peaking when the thickness defines an integer number of half wavelengths at the output wavelength. Therefore there are several thicknesses at which the optical output peaks, and preferably, the total LEP + HIL thickness matches one of these thicknesses. For example, in one structure, R, G, and B color (sub) pixels have the following layer thickness:

Generally, the other layers in the device have substantially the same thickness for R, G, and B color (sub) pixels.

When printing the HIL layer, each nozzle prints the HIL, but there is a different target layer thickness. The layer thickness of the HIL may also vary systematically depending on the position in a zone-for example to compensate for the reduced output intensity originally at one edge of a zone or at one end or the other end of a zone.

The technique previously described by me to match the volume output of the nozzles of a printing head to within a tolerance of 1% has an essential assumption: all nozzles function in the same way, but experiments have shown that this should not be the case. A typical SX3 print head has a nozzle diameter of 20 μm and a nozzle distance of 508 μm. The nozzle leads to a flat nozzle plate and is connected to a reservoir via a rocker filter acting as a screen through a restriction member positioned there by a piezoelectric transducer. The deposited material has a syrup-like consistency of 8 to 10 centipoise viscosity; once sprayed, the droplet may have a volume of 8 pL order. All nozzles function slightly differently for several reasons: the nozzle itself has a slightly varying size due to manufacturing tolerances, the head is divided into even nozzles and odd nozzles (this is driven by a separate group of head electronics that are not precisely matched ); And there are other factors to consider.

We will describe the technique of tuning the output droplet volume in a single print head to allow three different droplet volumes to be printed in the R, G, and B positions within a single print strip area. The nozzles on the print head are divided into three groups and each of these groups is tuned to target the relevant droplet volume for the optimal cavity thickness desired for each color. Figure 4 illustrates the different methods used for red, green and blue in a method according to an embodiment of the invention Examples of the same droplet size. The technique I have described is suitable for both the single print head system and the multi-head print bar used in the production of inkjet printed OLED displays.

FIG. 5 shows a typical print head driving waveform illustrating a voltage applied to a piezoelectric transducer. This starts at an initial voltage level V1 (eg 135V) that can effectively be regarded as a zero or reference voltage level. Next, the voltage is reduced to V2, which can be, for example, about 85V in this example, giving a voltage difference of 50 volts. Then, the voltage returns to a third value V3, which may be the same as or different from the first value V1, and the cycle then continues.

Generally, to initiate a droplet, a voltage difference is formed across the PZT at the local end of a particular nozzle. The voltage at one electrode at the PZT of the nozzle is a fixed voltage and is common to all nozzles (commonly referred to as common rail). All waveform parameters only affect the other variable electrode. When stationary, V1 (starting voltage) is equal to or similar to the common rail. In general, the final voltage tank (V3 in the figure) is also equal to or similar to the common rail (but in theory, between the variable electrode and the common rail (which does not start a droplet but keeps PZT between start events There may be a voltage difference between a stress state).

In a typical repetitive burst stream, the first phase may have, for example, a duration of 3 μs, the second phase has a duration of 5 μs and the third phase has a duration of 3 μs. Droplet ejection occurs during the transition between phase two and phase three; before that, the nozzle "filled up." If the value of the voltage V2 is reduced to increase the voltage step between V1 and V2, the volume of the droplet increases.

However, this is a simplification of nozzle behavior and an attempt to determine a linear scaling factor between the volume of the nozzle of a print head and the voltage V2 has not performed well because the speed-voltage-volume relationship is non-linear and the print head The overall behavior is complex.

Initially, the relationship between the pulse width of the waveform and the resulting volume is determined (adjusting the pulse width on a waveform has the greatest effect on the output droplet volume-the longer the pulse width, the larger the droplet volume). Therefore, in one method, all nozzles are set to a first pulse width (for example, a short pulse width such as 3 μs) under a fixed driving voltage, and then, they are printed All the nozzles in the machine are individually printed onto a collimated sample on a flat substrate. With the same fixed voltage, the nozzles are then all set to a second pulse width, preferably a much longer pulse width of, for example, about 7 μs. Then print a second collimated sample. Next, for example, a Zygo white light jammer is used to measure the thickness of each individually printed droplet from each of the collimated samples. This provides one of the deposition thicknesses of the dry material, and the volume of each droplet can be determined based on the volume concentration of the initial solution. Then, this volume can be correlated with the pulse width for each printed droplet to allow (in this particular example) a pulse width and volume relationship for each individual nozzle to be determined within a range of 4 μs. FIG. 6 schematically shows the short pulse width 510 and the long pulse width 520 and the corresponding droplet volume produced by the printer head nozzle.

Preferably, the pulse width value at each end of the range is determined to allow interpolation, rather than extrapolation beyond the measured range. Preferably, one or more intermediate pulse widths are also used to allow one of the pulse width and volume relationships to be more accurately mapped. Preferably, each thickness value is measured multiple times (e.g. 10 times) and preferably there are multiple (e.g. 10) repeated depositions of a droplet at each pulse width thus giving a substantial amount of data ( For example, there may be 128 nozzles, each with 100 repetitions). Preferably, a substrate with a hydrophobic coating is used to collimate the sample.

Based on this collimation, the three discrete pulse widths required to approximate the target thickness of the HIL and / or IL thickness of each color sub-pixel of the OLED display are selected.

Then, to more accurately select the discrete volume target / thickness, the relationship between the driving voltage and volume of each pixel is also collimated.

Therefore, a waveform having a pulse width (in its repeated RGB pattern) determined for the target volume / thickness is set using the same measurement procedure as explained above. The drive voltage is set to the same value across all nozzles and then a collimated sample is printed. The driving voltage across all nozzles is then set to a different value, for example 5 volts higher than the first value, and then a second collimated sample is printed. Then, use the Zygo jammer as previously explained to measure these The samples are collimated, and the output volume data is then correlated with the nozzle position to determine a relationship between the drive voltage at each nozzle's relative pulse width and the droplet volume / deposited material thickness. As explained previously, since powering one nozzle can affect the other nozzle, it is preferable to print a collimated sample under conditions similar to those used in manufacturing the actual device. For example, when printing a (vertical) column of collimated dots as used during device manufacturing, the head can be rotated to the same pitch (angle of nozzles in the column relative to the direction of movement of the head)-so that nozzle firing has similar timing.

Preferably, the procedure is then repeated to fine tune to the target volume / thickness by adjusting the driving voltage repeatedly and measuring the thickness / volume to get closer to the target deposition thickness / volume. Figure 7a shows an exemplary mapping of measured droplet volume against the drive voltage (pulse step) of a set of nozzles of a printer head.

Although in principle the pulse width or driving voltage can be varied on its own to achieve a desired target deposition thickness / droplet volume, it is preferred to vary both to achieve a more accurate result.

Although the illustrated example waveforms are simple, those skilled in the art should understand that more complex drive waveforms can be used instead. For example, FIG. 7b shows an example of a driving waveform with a droplet splitting pulse 710 after the main pulse to provide a cleaner cut of one of the ejected droplets. The first pulse starts the droplet but it also starts a small pressure wave (a bit like an echo) that continues after the start event is completed, and a second pulse is used to cancel the after-effect of the first pulse. The period between the first pulse and the second pulse, the intensity of the second pulse, or the drive is adjusted so that it fails to initiate a droplet itself but gives a cleaner and clearer disconnect, thereby reducing the number of satellite droplets and reducing Crosstalk to other nozzles.

A second alternative waveform in FIG. 7b shows a waveform that exhibits some excessive overshoot at 720 and gradually returns to one of the initial voltage values. When the printer has a facility for adjusting the associated fall time or negative slope, this can help to smoothly eject a sequence of droplets to give improved repeatability.

Those skilled in the art should understand that these and other changes in the shape of the drive pulse waveform Dynamic systems are possible, and one of the collimation procedures as explained above can be used to collimate these shape changes.

Once the waveform for each individual nozzle has been determined, the waveform data can be provided to the inkjet printer as a waveform file stored on a storage medium or via a computer network. An example of such a waveform file for a Litrex printer includes data for each nozzle that defines a voltage level and duration, for example, 9 bits are used to define 0V and a track voltage ( Such as 135V). Therefore, in order to define the printed waveform, it is only necessary to load a text file that defines this waveform data into the printer.

We have described techniques for using discrete volume targets for individual nozzles within a print head. For example, every third nozzle from nozzle 0 can be tuned to a specific droplet volume (eg red), every third nozzle from nozzle 1 can be tuned to another target droplet volume (eg green) and from nozzle 2 Every third nozzle can be tuned to a third target droplet volume (such as blue). This allows an OLED or organic PV (photovoltaic) substrate to achieve a desired HIL / IL thickness to provide the best LEP performance in a single pass of HIL / IL deposition. This saves a completely substantial amount of manufacturing time during the manufacture of this device. For larger volume differences / improved accuracy, both pulse width and dry voltage can be adjusted.

Those skilled in the art should realize that the above technology is not limited to the use in the manufacture of organic light-emitting diodes (small molecules or polymers), but can be used in materials where the material is dissolved in a solvent and deposited by a droplet deposition technique In the manufacture of any type of molecular electronic device. There is no doubt that those skilled in the art will think of many effective alternatives and it should be understood that the present invention is not limited to the illustrated embodiments, but includes modifications that are understood by those skilled in the art within the scope of the appended patent applications .

Claims (20)

A method of manufacturing an organic electronic device, the method comprising: providing a substrate having at least two sets of material deposition regions, a first set of material deposition regions for a first set of components of the device and a first Two sets of material deposition areas are used for a second set of elements of the device, wherein the first set of material deposition areas and the second set of material deposition areas have different first targets of different materials to be deposited into the areas Thickness and second target thickness; providing at least one solution of materials to be deposited on the first set of material deposition areas and the second set of material deposition areas; and by using a piezoelectric transducer to convert The solutions of the material are inkjet printed onto the first set of material deposition areas and the second set of material deposition areas; wherein the inkjet printing includes: depositing the at least one solution of the material using a print head including a plurality of nozzles , Each of the nozzles has an orifice of the same diameter, a first subset of the nozzles is used for deposition onto the first set of material deposition areas, and the A second subset of equal nozzles for deposition onto the second set of material deposition areas; and a first driving waveform to drive the first subset of nozzles and a different second driving waveform to drive the first Two subset nozzles for depositing the materials of different respective first target thickness and second target thickness, wherein the deposition includes the solution from the nozzles of the first subset and the second subset of nozzles The same number of droplets are deposited onto the first group of material deposition regions and the second group of material deposition regions. The method of claim 1, which includes depositing the same solution of material onto both the first set of material deposition regions and the second set of material deposition regions. The method of claim 2, wherein the material includes a material for a hole injection layer and / or interlayer of the device. The method of claim 1, comprising providing a first solution and a second solution of materials to be deposited on the respective first group of material deposition regions and the second group of material deposition regions; and wherein the deposition includes depositing from the The first solution and the second solution of the materials of the first subset and the second subset are separated by equal nozzles. The method of any one of claims 1 to 4, wherein the inkjet printing includes printing in a strip area, and wherein the deposition includes depositing the target thickness of material in a single strip area. The method of claim 1, wherein the number of droplets is a single droplet. The method of claim 1, wherein the depositing includes depositing a single droplet of the solution from a single nozzle of the first subset and the second subset of nozzles onto each printing position. The method of claim 1, wherein the first driving waveform and the second driving waveform include first and second pulses of different respective durations, a longer duration is used for a larger target of the deposited material thickness. The method of claim 8, wherein the first driving waveform and the second driving waveform include a first voltage step and a second voltage step, the method includes applying the same duration to the thickness of the deposited material Coarse control and use these equal voltage steps for fine control of the thickness of the deposited material. The method of claim 1, further comprising determining that the first driving waveform and the second driving waveform are respectively one of the respective first subset of nozzles and the respective second nozzle in the respective second subset. The method of claim 1, further comprising calibrating individual nozzles of the print head as the duration and voltage steps of a pulse-type driving waveform change to determine the pulse duration and pulse voltage steps to be used for a nozzle A combination to deposit a material with a determined thickness. The method of claim 1, further comprising storing data defining a first group of the first driving waveform and a second group of the second driving waveform on a non-volatile storage medium, and a driving waveform is used for the first of the nozzle Each nozzle in the subset and the second subset; and providing the stored data to an inkjet printer for controlling the print head of the printer. The method of claim 1, which is used with the substrate having at least three sets of the material deposition areas, the method comprising using three such subsets of nozzles with different respective drive waveforms to inject the solution of material It is printed on three sets of these material deposition areas for depositing three different materials of the target thickness. The method of claim 1, wherein one of the regions includes a well region on the substrate. The method of claim 1, further comprising drying the substrate to leave the material in the material deposition areas; and using the dried substrate to manufacture the organic electronic device. The method of claim 1, wherein one of the regions defines an organic diode. The method of claim 16, wherein each of the regions defines an organic light emitting diode OLED, and wherein the organic electronic device is an OLED display. A method of tuning the color cavity of a color OLED display using the method of claim 17, wherein each group of areas defines a respective group of color OLED sub-pixels (sub-pixels), each sub-pixel having a corresponding A different target optical cavity length of a different different color, and wherein the target thickness of the material is determined according to the target optical cavity length. The method of claim 18, wherein the target optical cavity length is defined by a combination of a thickness of a light emitting layer of each OLED and a thickness of a hole injection layer, and wherein the method is used to deposit the light emitting layer and the The hole is injected into one or both of the layers. An ink jet printer includes an computer that stores instructions and a storage component. When loaded into the computer and executed, the instructions are executed as described in any of items 1-19 One way.