A kind of preparation method of quantum dot photodetector

Abstract

The invention belongs to the field of optical material preparation, and specifically discloses a preparation method of a quantum dot photodetector, comprising the following steps: S1 preparing a ligand atmosphere: dissolving an organic ligand in a solvent to form a ligand solution, making the ligand The solution fills the entire confined space in the form of gas, and then prepares to obtain a ligand atmosphere; S2 prepares a quantum dot gas passivation film: prepares a quantum dot film on the substrate, and places the substrate prepared with the quantum dot film on the ligand prepared in step S1. In the bulk atmosphere, the organic ligands in the ligand atmosphere passivate the surface of the quantum dots; S3 prepare quantum dot photodetector electrodes: finally prepare electrodes on the surface of the passivated quantum dot film to prepare quantum dot photodetectors. The invention can greatly reduce the generation of dark current, and the passivation of organic ligands is more uniform, which is beneficial to large-scale production of photodetectors and saves organic ligands.

Description

technical field [0001] The invention belongs to the field of optical material preparation, and more specifically relates to a preparation method of a quantum dot photodetector. Background technique [0002] Quantum dots, also known as nanocrystals, are nanoparticles composed of II-VI or III-V elements. The particle size of quantum dots is generally between 1 and 10 nm. Since electrons and holes are quantum-confined, the continuous energy band structure becomes a discrete energy level structure with molecular characteristics, and can emit fluorescence after being excited. The emission spectrum of quantum dots can be controlled by changing the size of the quantum dots. It has good photostability, wide excitation spectrum and narrow emission spectrum. It has a wide range of applications in the fields of solar cells, light-emitting devices, and optical biomarkers. application prospects. [0003] At present, in the field of quantum dot photodetector preparation, ligand exchange...

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Problems solved by technology

[0004] For example, CN106701060A discloses a kind of passivation and passivation method of quantum dot film, which specifically replaces all the oleic acid ligands on the surface of quantum dots with halogen ligands. Its essence is to use the solution method to exchange ligands. While improving the electron transmission rate, it also increases the dark current, which is not conducive to improving the light / dark current ratio of the device for photodetectors. At the same time, the solution-based ligand exchange process is more complicated than the gas-phase passivation method, which is not conducive to practical applications. Large-scale production; CN106085417A discloses a kind of preparation method of water-soluble quantum dot, specifically is that the oil-soluble ligand (oleic acid, oleylamine) on the quantum dot surface adopts liquid phase method to replace it with hydrophilic ligand (multiple mercapto polymer), its essence is to use the solution method to carry out ligand exchange, and the water-soluble ligand used in it has poor carrier transport performance, which is not conducive to the preparation of quantum dot photodetectors, and the reaction time is long (10h), and the steps are complicated The operation is difficult and unfavorable for large-scale production; CN105247010A discloses a solvent-free quantum dot exchange method, specifically using a low-viscosity silane polymer instead of a solvent to exchange ligands on the surface of quantum dots, and its essence is to use a solution Ligand exchange method for quantum dots, the silane precursor can only be used in the field of lighting, can not be used in the field of optoelectronics, its essence is only the encapsulation of quantum dots does not improve the optoelectronic performance of the device, there is a high preparation temperature, easy to destroy quantum Point problems and defects; CN106367060A discloses a ligand exchange method for quantum dots, which is specifically to hydrolyze oil-soluble quantum dots by adding esterified compounds to obtain water-soluble quantum dots. High temperature, poor electron transport performance, not suitable for problems and defects of optoelectronic devices; CN106206972A discloses a preparation method of quantum dot light-emitting layer, specifically, using a solution method to replace short-chain ligands with long-chain ligands to improve quantum dot luminescence The essence of the carrier mobility of the device is to use the solution method for ligand exchange, which is not conducive to mass production, and there is a problem of large dark current for photodetectors

[0005] The existing ligand exchange is carried out by the solution method. The preparation of photodetectors by this method requires high technology and wastes a lot of ligands, which is not conducive to large-scale production. Compared with ligands with large dark currents such as EDT, after After ligand exchange, quantum dot photodetectors have disadvantages such as low photo-dark current ratio and slow response time.

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