TWI699922B - Method for manufacturing large-area organic photodiode - Google Patents

Abstract

The present invention discloses a method for manufacturing large-area organic photodiode. The organic photodiode is prepared by spraying. Improving the performance of organic photodiode by the smoothing process for improving the surface layer smoothing and the annealing process for enhancing the contact quality of each interface. The sensitivity of the organic photodiode is enhanced by effectively reducing the dark current and increasing the on/off ratio.

Description

Manufacturing method of large area organic photoelectric diode

The present invention relates to a method for manufacturing a photodiode, especially a method for manufacturing a large-area organic photodiode.

An organic photodiode (OPD) is a photodiode made of organic materials, which can be converted into a current or voltage signal after receiving light energy for use as a light sensor.

In addition, organic photodiodes (OPD) have the characteristics of light weight, low cost, and flexibility, so they can be used to replace traditional photodiodes or optoelectronic components based on inorganic materials. Furthermore, organic materials are only sensitive to specific wavelengths of light, so by selecting suitable materials, the spectral sensitivity of the photoelectric sensor can be controlled.

These features expand the scope of OPD applications, including: pulse oximeters, optical biosensors, digital X-ray image sensors, low-cost spectrometers, finger sensors, gesture sensors, and array sensors.

Generally speaking, the structure of an organic photodiode includes an anode, an active layer, and a cathode. The active layer is composed of an electron donor and an electron acceptor, which generates holes after receiving light energy. -Electron pair, and the hole-electron pair separation produces two kinds of electric charge, electron and hole, so that the hole can move in the direction of the anode, and the electron moves in the direction of the cathode. Electric current is generated by transferring the charge to the corresponding electrode. Therefore, the active layer is an important structure that affects the photoelectric conversion performance, and the crystalline structure, surface shape, and thickness of the active layer materials are all factors that affect the performance of the organic photodiode.

In the conventional preparation of organic photodiodes, most of the thin film structures are formed by spin coating. Although this method can obtain a thin film structure with better flatness and uniformity, it is limited by the operation The method cannot be applied to the preparation of large-area organic photoelectric diodes and lacks industrial applicability.

In addition, due to the poor solubility of organic materials, the concentration of the solution is not easy to increase, so that the thickness of the active layer cannot be effectively increased when the active layer is prepared by spin coating. If the thickness of the active layer is insufficient, leakage is likely to occur, which means darkening. The dark current increases and the on/off ratio relatively decreases.

The dark current can also be called leakage current, which is based on the bulk resistivity of the active layer material, and the current flowing through the organic photodiode under no light, the darker current The smaller means the smaller the leakage. Relatively speaking, when the organic photodiode is illuminated, the current generated by the hole in the active layer moves toward the anode and the electron moves toward the cathode. The current generated is called photocurrent (photocurrent ), and in fact, the photocurrent measured from the organic photodiode is a combination of the current generated during illumination and the dark current. Therefore, the dark current must be minimized to improve the sensitivity of the organic photodiode to light (sensitivity), and expressed by the ratio of photocurrent to dark current, which is the on/off ratio.

In summary, in the existing technology, improving the crystalline structure, surface shape and thickness of the active layer material can all improve the performance of the organic photodiode. Therefore, it is necessary to further develop methods to solve the problem of insufficient thickness of the active layer, improve the granular surface, and improve the quality of the contact surface between the active layer and the electrode.

One objective of the present invention is to provide a method for manufacturing a large-area organic photodiode, which uses a spraying process to make the thickness of the active layer greater than 500 nanometers, thereby reducing the dark current of the organic photodiode and improving the switching ratio .

Another object of the present invention is to provide a method for manufacturing a large-area organic photodiode. After the active layer is formed, a solvent is sprayed on the active layer, so that the surface particles of the active layer are flattened, thereby improving the charge conduction effectiveness.

Another object of the present invention is to provide a method for manufacturing a large-area organic photodiode, which performs the annealing process after the active layer is formed and the metal electrode is formed, so that the surface contact between the active layer and the metal electrode is better. Good, it can effectively reduce the dark current, thus improving the efficiency of the organic photodiode.

In order to achieve the above objective, the present invention discloses a method for manufacturing a large-area organic photodiode. The steps include: providing a conductive substrate; performing a spraying process to form a charge transport layer and an active layer on the conductive substrate The active layer is disposed on the charge transport layer; a leveling process is performed to level the surface particles of the active layer; a metal electrode is deposited on the active layer; and an annealing process is performed.

The present invention provides an embodiment, the content of which is a method for manufacturing a large-area organic photodiode, wherein the spraying process further includes the steps of: spraying the charge transport layer on the conductive substrate; and spraying the active layer On the charge transport layer.

The present invention provides an embodiment, the content of which is a manufacturing method of a large-area organic photodiode, wherein the conductive substrate further includes a glass conductive substrate or a flexible conductive substrate.

The present invention provides an embodiment, the content of which is a manufacturing method of a large-area organic photodiode, wherein the charge transport layer further includes a conductive polymer or a metal oxide.

The present invention provides an embodiment, the content of which is a method for manufacturing a large-area organic photodiode, wherein the active layer further includes a poly(3-hexylthiophene) and a fullerene derivative.

The present invention provides an embodiment, the content of which is a method for manufacturing a large-area organic photodiode, wherein after the spraying process, the thickness of the active layer is greater than 500 nanometers (nm).

The present invention provides an embodiment, the content of which is a manufacturing method of a large-area organic photodiode, wherein the leveling process step further includes the step of: spraying a solvent on the active layer.

The present invention provides an embodiment, the content of which is a manufacturing method of a large-area organic photodiode, wherein the solvent is 1,2-dichlorobenzene.

The present invention provides an embodiment wherein the content of manufacturing a large-area organic photodiode of the method, wherein the temperature of the annealing process is between 170 ~ 190 ^o C.

In order to enable your reviewer to have a better understanding and understanding of the features of the present invention and the effects achieved, the following examples and accompanying descriptions are provided here:

In view of the influence of the leakage phenomenon on the organic photodiode, the present invention proposes a method for manufacturing a large-area organic photodiode to solve the problems caused by the conventional technology.

In the following, the characteristics included in the manufacturing method of the large-area organic photoelectric diode of the present invention, the matched structure and the method will be further described:

Please refer to Figure 1, which is a flowchart of an embodiment of the present invention. As shown in the figure, the method of manufacturing a large-area organic photodiode disclosed in the present invention includes the following steps:

S1: Provide conductive substrate;

S3: Perform a spraying process to form a charge transport layer and an active layer on the conductive substrate, and the active layer is provided on the charge transport layer;

S5: Carry out leveling treatment to level the surface particles of the active layer;

S7: Depositing a metal electrode on the active layer; and

S9: Perform annealing process.

As shown in step S1, a conductive substrate 1 serves as the anode of a large-area organic photodiode, and the conductive substrate further includes a glass conductive substrate or a flexible conductive substrate, but not limited to this. The conductive substrate, such as the conductive layer, is preferably Indium Tin Oxide (ITO).

Then, as shown in step S3, a step of a spraying process further includes the steps of: spraying a charge transport layer 2 on the conductive substrate 1 (as shown in FIG. 2A); and spraying an active layer 3 on the conductive substrate 1 On the charge transport layer 2 (as shown in Figure 2B). Moreover, the charge transport layer 2 further includes a conductive polymer or a metal oxide, which has good charge conductivity and light transmittance. However, the active layer 3 is a key structural layer for photoelectric conversion, and the active layer 3 can be selected from a polymer material that can be used as an electron donor and a fullerizer as an electron acceptor. Ene derivative materials. In this embodiment, the active layer further includes a poly(3-hexylthiophene) and the fullerene derivative.

Furthermore, following the above, in this embodiment, the active layer 3 material is formed layer by layer on the charge transport layer 2 of the conductive substrate 1 through the spraying process. After the spraying process, the thickness of the active layer 3 is greater than 500 nm ( nm) above.

Then please match the figures 3A-3C, which are the voltage and current density comparison diagrams of different active layer thicknesses of the present invention, the dark current density comparison diagrams of different active layer thicknesses of the present invention, and the different active layers of the present invention. Comparison chart of quantitative data of thickness. As shown in Figure 3A, the on/off ratio (on/off) also increases as the thickness of the active layer 3 increases. As shown in Figure 3B, the dark current increases with the thickness of the active layer 3. However, the figure 3C shows that increasing the thickness of the active layer 3 by the spraying process can reliably and effectively improve the performance of the large-area organic photodiode.

Then, as shown in step S5, one of the leveling treatment steps further includes the step of spraying a solvent 4 on the active layer 3 (as shown in Figure 2C), where the solvent 4 is a 1,2-dichloro Benzene (1,2-dichlorobenzene, DCB for short). In the process of spraying the solvent 4, the surface of the active layer 3 will become wetter, and the droplet boundary generated by the spraying process will be eliminated, which will hinder the effective conduction of electric charge. After the solvent 4 is volatilized, the boundary of the droplets on the surface of the active layer 3 can be effectively flattened to obtain the active layer 3 with a uniform surface, which improves the charge transfer and improves the interface between the active layer 3 and the metal electrode 5 contact.

Furthermore, as shown in step S7, the metal electrode 5 is deposited on the planarized active layer 3 (as shown in FIG. 2D).

Finally, as shown in step S9, wherein the temperature of the annealing process is between 170 ~ 190 ^o C. While the present embodiment places 180 ^o C as the temperature of the annealing process, the anneal time is 10 minutes, but is not limited thereto.

Continue the above, and please match Figure 4, which is a comparison diagram of the annealing process of the present invention. As shown in the figure, if the annealing process (pre) is performed before the deposition of the metal electrode 5, only the crystalline structure of the active layer 3 is simply improved. Compared with none of the annealing process (none), the dark current and switching ratio There are obvious improvements. However, if the annealing process (post) is performed after the metal electrode 5 is deposited, in addition to improving the crystallization of the active layer 3, it can also improve the interface contact between the active layer 3 and the metal electrode 5. The organic photodiode Compared with the organic photodiode that is annealed (pre) first, the performance of the photoelectric diode is significantly improved.

Therefore, the present invention is really novel, progressive, and available for industrial use. It should meet the patent application requirements of my country's patent law. Undoubtedly, I filed an invention patent application in accordance with the law. I pray that the Bureau will grant the patent as soon as possible.

However, the above are only the preferred embodiments of the present invention, and are not used to limit the scope of implementation of the present invention. For example, the shapes, structures, features and spirits described in the scope of the patent application of the present invention are equally changed and modified. , Should be included in the scope of patent application of the present invention.

S1~S9‧‧‧Step 1‧‧‧Conductive substrate 2‧‧‧Charge transport layer 3‧‧‧Active layer 4‧‧‧Solvent 5‧‧‧Metal electrode

Figure 1: It is a flow chart of an embodiment of the present invention; Figures 2A-2D: It is a schematic flow diagram of an embodiment of the present invention; Figure 3A: It is a different active layer thickness of the present invention Figure 3B: It is a comparison diagram of dark current density of different active layer thicknesses of the present invention; Figure 3C: It is a comparison diagram of quantitative data of different active layer thicknesses of the present invention; and Figure 4: It is a comparison diagram of the annealing process of the present invention.

S1‧‧‧Provide conductive substrate

S3‧‧‧A spraying process is performed to form a charge transport layer and an active layer on the conductive substrate, and the active layer is provided on the charge transport layer

S5‧‧‧Smoothing the surface particles of the active layer

S7‧‧‧Deposit metal electrodes on the active layer

S9‧‧‧Annealing process

Claims (7)

A method for manufacturing a large-area organic photodiode, the steps comprising: providing a conductive substrate; performing a spraying process to form a charge transport layer and an active layer on the conductive substrate, the active layer being provided on the charge transport On the layer; performing a leveling treatment, spraying a solvent on the active layer to flatten the surface particles of the active layer, the solvent is 1,2-dichlorobenzene; depositing a metal electrode on the active layer; And performing an annealing process. The method for manufacturing a large-area organic photodiode according to the first item of the scope of patent application, wherein the spraying process further includes the steps of: spraying the charge transport layer on the conductive substrate; and spraying the active layer On the charge transport layer. The method for manufacturing a large-area organic photodiode as described in the first item of the patent application, wherein the conductive substrate further includes a glass conductive substrate or a flexible conductive substrate. The method for manufacturing a large-area organic photodiode as described in the first item of the patent application, wherein the charge transport layer further includes a conductive polymer or a metal oxide. The method for manufacturing a large-area organic photodiode as described in the first item of the scope of patent application, wherein the active layer further comprises a poly(3-hexylthiophene) and a fullerene derivative. The method for manufacturing a large-area organic photodiode as described in the first item of the scope of patent application, wherein after the spraying process, the thickness of the active layer is greater than 500 nanometers (nm). The method for manufacturing a large-area organic photodiode as described in item 1 of the scope of patent application, wherein the temperature of the annealing process is between 170 and 190°C.

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