Preparation,Optical Properties And Application Of Ⅰ-Ⅲ-Ⅵ Alloy Quantum Dots

Colloidal quantum dots have been favored by more and more researchers in recent years due to their superior properties such as size control,wide range of illumination,and simple synthesis methods.It has been widely used in the fields of display lighting,biomedicine,infrared detectors,solar cells,etc.Nowadays,synthesis methods of quantum dot have developed rapidly,and optical properties of quantum dot,including the quantum yield and stability,have improved gradually.Currently,researchers have synthesized a variety of high-quality nanomaterials,and quantum dot-based products are appearing on the market gradually.However,at present,the most popular materials usually contain heavy metals such as Cd,which is harmful to human health and the environment.Therefore,developing non-toxic quantum dot materials without heavy metals has been given extensive attention.Based on the concept of"green"environmental protection concept,this paper prepared multinary-quantum dots without Cd element,such as ternary CuInS₂/ZnS quantum dots and quaternary AgInGaS₂ quantum dots,and applied them to electroluminescent diodes,photoluminescent diodes,and perovskite solar cells.The specific innovation results are given as follows:（1）CuInS₂ quantum dots were synthesized by high temperature thermal injection.The CuInS₂/ZnS quantum dots were synthesized after coating the ZnS shell.The emission wavelength of CuInS₂/ZnS quantum dots in the range of 580⁸00 nm was finely tuned.The charge injection is affected by the difference in conductivity of the surface ligand,which further affects the luminous efficiency of the light emitting diode.We synthesized CuInS₂/ZnS quantum dots of two different surface ligands（n-dodecyl mercaptan and octyl mercaptan）for comparative study,and prepared CuInS₂/ZnS quantum dot-based electroluminescent diodes.Finally,the maximumηEQE of QLED prepared by synthesizing CuInS₂/ZnS quantum dots based on 1-octylthiol was 3.36%at 2.8V.The maximum current density at 3.2V was 0.48 cd/A,and the maximum luminescence intensity at 7.6V was 113.83 cd/m².It has better luminescent properties.（2）The peak wavelength of CuInS₂/ZnS quantum dots can be adjusted in the range of 630-730 nm by controlling the element ratio.The quantum dots of different emission wavelengths were synthesized by using different Cu/In as a luminescent material in combination with a blue-emitting GaN chip and a green phosphor to prepare the WLED.The LEDs without red quantum dots have very low CCT and CRI values.Under the addition of red light-emitting CuInS₂/ZnS quantum dots,the obtained WLED performance has been greatly improved,with a high CRI value and a suitable CCT value.Among them,the WLED prepared by using a dark red emission quantum dot with Cu/In ratio of 1/4 has a CRI value of 91 and a CCT value of 6347K,which is suitable for general indoor illumination.（3）We synthesized quaternary AIGS quantum dots in octadecene（ODE）by thermal injection using oleylamine（OAm）and 1-n-dodecylmercaptan（DDT）as ligands and stabilizers.By changing the Ag/In ratio,the emission wavelength and energy level structure of the quantum dots can be tuned.The prepared quantum dots were added to the CsPbBr₃/Carbon interface of the PSCs,and the difference in energy levels was well adjusted and contributed to the extraction of holes.The prepared unsealed PSCs exhibited significant stability at room temperature,with a cell efficiency of 8.84%,which was 46.8%higher than the original device efficiency of 6.01%.This outstanding performance indicates that quaternary alloy quantum dots have potential applications in photoelectric conversion.