CN105514274B - It is a kind of based on lithium fluoride/polyvinyl alcohol alternate thin films organic semiconductor device thin film encapsulation technology - Google Patents

Abstract

The invention discloses a thin film encapsulation technology for organic semiconductor devices based on lithium fluoride/polyvinyl alcohol alternating thin films, which is characterized in that a lithium fluoride buffer layer (6) is prepared first, and then polyvinyl alcohol (701)/fluorine Lithium oxide (702) alternately encapsulates the film. The patented thin-film packaging technology is realized through the following steps: ① Deposit a lithium fluoride buffer layer on the organic semiconductor device (5) by vacuum thermal evaporation, and its scale is appropriate so that the electrodes (2 and 2) of the organic semiconductor device to be packaged 4) exposed outside, and its organic semiconductor active layer (3) is completely encapsulated inside; ② prepare polyvinyl alcohol encapsulation layer on the lithium fluoride buffer layer by spin coating; ③ carry out drying treatment; ④ in polyvinyl alcohol The lithium fluoride encapsulation layer is deposited on the encapsulation layer by vacuum thermal evaporation; ⑤Repeat the above steps ②-④, until the (N-1)th layer of polyvinyl alcohol/lithium fluoride alternately is prepared on the lithium fluoride encapsulation layer Thin film (NO); ⑥Heat the packaged device at 200°C for 2 hours to cross-link the polyvinyl alcohol.

Description

An organic semiconductor device thin film based on lithium fluoride/polyvinyl alcohol alternating thin film packaging technology

【Technical field】

The invention belongs to the field of packaging of organic semiconductor devices, in particular to a film packaging technology of organic semiconductor devices based on lithium fluoride/polyvinyl alcohol alternating thin films.

【Background technique】

In addition to the basic characteristics of inorganic devices, organic semiconductor devices also inherit the advantages of light weight, low cost, simple preparation process, good flexibility, easy large-scale and miniaturization of organic semiconductor materials, and have broad application prospects. Since the 1980s, many well-known companies and university research institutions, including IBM, Sony, Samsung, Princeton University and Cambridge University, have conducted a lot of research in the field of organic semiconductor devices. Currently, organic semiconductor devices mainly include organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs), and organic photovoltaic cells (OPCs).

The update speed of organic semiconductor devices is getting faster and faster, and its products are also developing towards the trend of lighter weight, smaller volume, thinner thickness and better performance. However, compared with inorganic devices, organic semiconductor devices show great shortcomings in terms of stability. Scientists found that the main factors affecting the life of organic electronic devices are water and oxygen in the air when they measured organic semiconductor devices in different humidity and different temperature test environments. They will infiltrate from the surface of the device, causing great damage to the organic semiconductor device, seriously affecting the performance of the organic semiconductor material and the electrode material, thereby seriously degrading the performance of the device. Therefore, the packaging of organic semiconductor devices is very important.

The traditional glass/metal back cover packaging method can basically meet the packaging requirements of the device in many cases, but with the continuous development of semiconductor manufacturing technology and the continuous improvement of technical requirements for chip packaging, the traditional packaging method has been unable to meet Devices require lighter and thinner packaging, and the cost of this packaging method is relatively high. The new packaging method to replace this traditional packaging method is to use thin film packaging. At present, the most commonly used thin film packaging methods include organic thin film packaging, inorganic thin film packaging, organic/inorganic hybrid thin film packaging, inorganic/inorganic thin film hybrid packaging, etc.

Inorganic films generally have good mechanical properties, and the films are usually continuous and very dense, and have a high barrier capacity for water vapor and oxygen. However, during the deposition process of the inorganic thin film, defects, such as pinhole-like cracks, etc. will inevitably be formed on the thin film; as the thickness of the thin film increases slowly, relatively large internal stress will be formed in the inorganic thin film packaging layer. The formation of these internal stresses and the generation of defects will make water vapor and oxygen easily enter the device through the inorganic thin film packaging layer, seriously affecting the performance of the device, and thus greatly reducing the packaging effect. Compared with inorganic thin films, organic thin films have good flexibility and can be well used for the packaging of flexible devices; the weight of devices encapsulated by organic thin films is also very light, and the cost performance of products is relatively high. However, compared with inorganic films, organic films have poor barrier properties to water vapor and oxygen.

Considering the advantages and disadvantages of organic and inorganic thin films, simply using organic or inorganic thin films to encapsulate organic electronic devices will make it easier for water vapor and oxygen to enter the device through the thin film encapsulation layer, which will seriously affect the performance of the device and lead to packaging failure. The effect is greatly reduced. At the same time, when the organic/inorganic thin film packaging method is used alternately, the pinhole-like defects in the inorganic thin film packaging layer and the internal stress of the thin film layer have been greatly reduced. Compared with the single-layer inorganic thin film packaging, the packaging The effect and quality have been significantly improved.

The thin film packaging technology for organic semiconductor devices based on lithium fluoride/polyvinyl alcohol alternating thin films provided by the present invention does not limit the type of organic semiconductor devices, and the inorganic material lithium fluoride used in it plays a very good role in protecting the packaging of devices , while the organic material polyvinyl alcohol can improve the encapsulation effect of lithium fluoride. The lithium fluoride/polyvinyl alcohol alternate film encapsulation can effectively improve the lifetime and stability of organic semiconductor devices.

【Content of invention】

The object of the present invention is to provide a thin film encapsulation technology for organic semiconductor devices based on lithium fluoride/polyvinyl alcohol alternating thin film.

The device packaged by the organic semiconductor device thin film packaging technology based on lithium fluoride/polyvinyl alcohol alternating thin film provided by the present invention has a structure as shown in Figure 1, including a substrate (1), an organic semiconductor device (5), a fluorinated Lithium buffer layer (6), first polyvinyl alcohol encapsulation layer (701), first lithium fluoride encapsulation layer (702), Nth polyvinyl alcohol encapsulation layer (N01), Nth lithium fluoride encapsulation layer (N02) The lithium fluoride buffer layer covers the organic semiconductor device, the first polyvinyl alcohol encapsulation layer covers the lithium fluoride buffer layer, the first lithium fluoride encapsulation layer covers the first polyvinyl alcohol encapsulation layer, The lithium fluoride encapsulation layer and the polyvinyl alcohol encapsulation layer may alternately overlap until the Nth lithium fluoride encapsulation layer, where N is an integer greater than or equal to 1. In this encapsulation technology, the width of the organic semiconductor device is smaller than the width of the substrate, and the encapsulation layer covers the entire organic semiconductor device; the preparation method of the lithium fluoride encapsulation layer is vacuum thermal evaporation, and the preparation method of the polyvinyl alcohol encapsulation layer is solution spin Coating method; the lithium fluoride buffer layer is used to prevent the polyvinyl alcohol aqueous solution from affecting the organic semiconductor device during the spin coating process.

The thin film packaging technology for organic semiconductor devices based on lithium fluoride/polyvinyl alcohol alternating thin films provided by the present invention comprises the following steps:

① Deposit a lithium fluoride buffer layer on the organic semiconductor device (5) by vacuum thermal evaporation, and its size is appropriate so that the electrodes (2 and 4) of the organic semiconductor device to be packaged are exposed outside, while the organic semiconductor is active. Layer (3) is fully encapsulated inside;

②Preparing a polyvinyl alcohol encapsulation layer on the lithium fluoride buffer layer by spin coating;

③After preparing polyvinyl alcohol for encapsulation, carry out drying treatment;

④ Deposit the lithium fluoride encapsulation layer on the polyvinyl alcohol encapsulation layer by vacuum thermal evaporation;

⑤ Repeat the above steps ②-④ until the (N-1)th layer of polyvinyl alcohol/lithium fluoride alternating film (NO) is prepared on the lithium fluoride encapsulation layer;

⑥Heating the packaged device at 200°C for 2 hours to cross-link the polyvinyl alcohol.

Technical analysis of the present invention:

A kind of encapsulation technology based on lithium fluoride/polyvinyl alcohol alternate film provided by the present invention first prepares a layer of lithium fluoride thin film on the surface of the organic semiconductor device by vacuum thermal evaporation method, and then spin-coats the smooth polyvinyl alcohol film as a The protection is good, and the influence of the water solvent on the device is reduced at the same time; then, the polyvinyl alcohol/lithium fluoride alternate film is prepared by a spin coating method and a vacuum thermal evaporation method to encapsulate the organic semiconductor device.

【Description of drawings】

Fig. 1 is a schematic structural view of an organic semiconductor device encapsulated by the thin film encapsulation technology provided by the present invention. In the figure, (1) is the substrate, (2) is the bottom electrode, (3) is the active layer, (4) is the top electrode, (5) is the organic semiconductor device, (6) is the lithium fluoride buffer layer, (701) is the first polyvinyl alcohol encapsulation layer, (702) is the first lithium fluoride encapsulation layer, (N01) is the Nth polyvinyl alcohol encapsulation layer, (N02) is the Nth lithium fluoride encapsulation layer.

【Detailed ways】

The present invention will be further described below by taking an organic semiconductor diode thin film package with the structure of "indium tin oxide (ITO) glass (conductive substrate)/copper phthalocyanine (active layer)/aluminum (top electrode)" as an example.

Example

In this embodiment, the packaging technology based on lithium fluoride/polyvinyl alcohol alternate film is used to encapsulate the organic semiconductor device according to the following steps:

1) Prepare copper phthalocyanine thin film and aluminum thin film by vacuum thermal evaporation method successively on the cleaned ITO;

2) The lithium fluoride buffer layer was prepared by vacuum thermal evaporation, the vacuum degree during evaporation was 1×10 ⁻³ Pascal, and the heating source used was a molybdenum boat. The evaporation rate of lithium fluoride is 6 angstroms/second, the time is 1 hour, and the thickness of the prepared lithium fluoride film is 2 μm;

3) The polyvinyl alcohol encapsulation film was prepared by spin coating, the rotation speed was 40 rpm within 9 seconds after the start of spin coating, and the subsequent rotation speed reached 3000 rpm, and the spin coating time was 3 minutes. The thickness of the prepared polyvinyl alcohol film is 1.13 μm;

4) After the polyvinyl alcohol encapsulation film is prepared, it needs to be dried in a constant temperature drying oven with a vacuum of 10 Pascals, a temperature of 40°C, and a time of 2 hours;

5) The lithium fluoride encapsulation thin film was prepared by vacuum thermal evaporation, the vacuum degree during evaporation was 1×10 ^-3 Pascal, the heating source used was a molybdenum boat, and the driving current of the heating source was 50A. The evaporation rate of lithium fluoride is 6 angstroms/second, the time is 1 hour, and the thickness of the prepared lithium fluoride film is 2 μm;

6) Repeat steps 2) to 5) to prepare 5 cycles of polyvinyl alcohol/lithium fluoride encapsulation film;

7) The packaged device is heated at 200° C. for 2 hours to cross-link the polyvinyl alcohol.

Claims (1)

1. an organic semiconductor device thin-film encapsulation method based on lithium fluoride/polyvinyl alcohol alternate film, it is characterized in that, at first prepare lithium fluoride buffer layer, then prepare polyvinyl alcohol encapsulation layer and lithium fluoride encapsulation layer successively; Wherein The lithium fluoride buffer layer covers the organic optoelectronic device, the first polyvinyl alcohol encapsulation layer covers the lithium fluoride buffer layer, the first lithium fluoride encapsulation layer covers the first polyvinyl alcohol encapsulation layer, and the fluorine The lithium fluoride encapsulation layer and the polyvinyl alcohol encapsulation layer are alternately overlapped to the Nth lithium fluoride encapsulation layer, where N is an integer greater than or equal to 1; The preparation method comprises the following steps: ① Deposit a lithium fluoride buffer layer on the organic semiconductor device by vacuum thermal evaporation, and its size is appropriate so that the electrodes of the organic semiconductor device to be packaged are exposed outside, while the organic semiconductor active layer is completely encapsulated inside; ②Preparing a polyvinyl alcohol encapsulation layer on the lithium fluoride buffer layer by spin coating; ③ Drying treatment; ④ Deposit the lithium fluoride encapsulation layer on the polyvinyl alcohol encapsulation layer by vacuum thermal evaporation; ⑤ Repeat the above steps ②-④ until the (N-1) layer of polyvinyl alcohol/lithium fluoride alternate film is prepared on the lithium fluoride encapsulation layer; ⑥Heating the packaged device at 200°C for 2 hours to cross-link the polyvinyl alcohol.