Organic electroluminescence device and preparation method thereof

Abstract

The invention belongs to the field of electroluminescence devices and discloses an organic electroluminescence device and preparation method thereof. The organic electroluminescence device comprises an anode substrate, a hole injection layer, a hole transport layer, an electron barrier layer, a luminescent layer, a buffer layer and a cathode layer, wherein the anode substrate, the hole injection layer, the hole transport layer, the electron barrier layer, the luminescent layer, the buffer layer and the cathode layer are sequentially laminated. The material of the buffer layer is metal fluoride. By arranging the buffer layer between cathodes and the luminescent layer, permeation on the luminescent layer from the cathodes can be effectively avoided, and transmission performance of electrons is protected. Meanwhile, fluorine in the buffer layer can form bonding effect with material of the cathode layer so that Fermi level of the buffer layer and the cathode layer can be reduced to the same level, the band of the buffer layer can be bent, contact potential barriers of the luminescent layer and the cathode layer can be effectively reduced, energy needing to be overcome when the electrons are transmitted to the luminescent layer is reduced, transmission capacity of the electrons in the organic electroluminescence device is improved, and therefore luminous efficiency of the organic electroluminescence device is achieved.

Description

technical field [0001] The invention relates to the field of electroluminescence devices, in particular to an organic electroluminescence device. The invention also relates to a preparation method of the organic electroluminescent device. Background technique [0002] In 1987, C.W.Tang and Van Slyke of Eastman Kodak Company in the United States reported a breakthrough in the research of organic electroluminescence. A high-brightness, high-efficiency double-layer small-molecule organic electroluminescent device was prepared using ultra-thin film technology. In this double-layer structure device, the brightness reaches 1000cd / m at 10V 2 , its luminous efficiency is 1.51lm / W, and its lifespan is more than 100 hours. In 1990, Burronghes et al. of the University of Cambridge proposed for the first time to use polymer conjugated polymer polyphenylene vinylene (PPV) to make polymer electroluminescence (EL) devices. Subsequently, the experimental group led by Professor Heeger of ...

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Problems solved by technology

[0004] In traditional electroluminescent devices, since the transport rate of electrons is two orders of magnitude lower than that of holes (the hole transport rate is generally 10 -3 cm 2 V -1 S -1 , the electron transfer rate is generally 10 -5 cm 2 V -1 S -1 ), this difference in rate often results in a low probability of exciton recombination, and the energy level difference between the cathode layer and the organic functional layer in the electroluminescent device is too far away. The work function of the cathode layer is generally -4.2eV, and the organic function The LUMO energy level of the layer (the electrons are transmitted from the cathode through the LUMO energy level of the organic functional layer to the light-emitting layer and recombined with holes to emit light) is generally -3.0eV, and the energy barrier between the two is relatively large, and electron transport needs to overcome more energy, which is not conducive to reducing the start-up voltage and current efficiency of organic electroluminescent devices; at the same time, the cathode layer is generally metal, and metal ions will penetrate into the organic functional layer, destroying the structure of the organic functional layer, generating electron traps, and capturing electrons. , so that the annihilation of electrons affects the recombination of excitons, and finally affects the luminous efficiency, making the luminous efficiency low

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