Defects And Performance Optimization Of CsPbBr₃ Doped Quantum Dots

In recent years,all-inorganic lead halide perovskite(CsPbX₃,X=Cl,Br,I)has attracted wide attention as a new generation of semiconductor materials.They demonstrate remarkable performance across different fields,including but not limited to solar cells,light emitting diodes(LEDs),photodetectors,and lasers.Owing to their narrow emission linewidth,tunable optical bandgap and wide color spectrum,lead halide perovskite quantum dots(HPQDs)are expected to emerge as next-generation light emitters for LEDs.Over the past few years,our understanding of doped halogenated perovskites has exploded,showing unique optical and electronic properties compared to undoped perovskites and improving the performance of perovskite optoelectronic devices.However,a series of fundamental scientific questions remain to be answered in the field of doping perovskites.In this paper,we mainly introduce the synthesis,properties and functional applications of metal-doped halogenated perovskite.And this paper mainly introduces the optimization of the performance of perovskite quantum dots through doping engineering.The main research contents are as follows:(1)CsPbBr₃ quantum dot solutions with different Ni(NO₃)₂ doping concentrations were prepared by hot injection method.The morphology and optical properties of CsPbBr₃ quantum dots with different doping ratios were tested,and the optimal doping ratio of 20% was obtained.X-ray diffraction(XRD)and X-ray electron spectroscopy(XPS)were used to measure the change of the structure of the doped material.Finally,we tested the structure stability and fluorescence intensity stability of undoped and Ni(NO₃)₂-doped CsPbBr₃ quantum dots.The results show that the successful incorporation of Ni²⁺optimizes the structure of the perovskite octahedron and reduces the defects of the perovskite to a large extent.(2)Inspired by Ni²⁺doping,we further studied the effect of Co²⁺doping with similar ion radius on the properties of CsPbBr₃ quantum dots.Based on previous work experience,we still choose 20%doping concentration.In order not to introduce new anionic impurity and cause new impurity center,we use CoBr₂ as dopant.Similarly,the optical properties and structural stability of the undoped and doped CsPbBr₃quantum dots were tested.In order to enable the material to be used in the device,we also tested the density and flatness of the quantum dot films by scanning electron microscopy(SEM)and atomic force microscopy(AFM).The film forming state has a great influence on the luminescence of the next device.(3)Based on the work of CoBr₂,20%Co(CH₃COO)₂(Co(AC)₂)was also used as dopant to add CsPbBr₃ quantum dots.Co(AC)₂ doped CsPbBr₃ quantum dots obtained the highest fluorescence quantum yield.We demonstrate the involvement of CH₃COO^- in bonding by XPS and Fourier transform infrared(FTIR)tests.In order to get better application of quantum dot materials,we also tested the stability of the quantum dot solution and the film.The luminescence performance and stability of CsPbBr₃ perovskite quantum dots are improved remarkably by simultaneous doping and surface passivation.As material performance verification,we used undoped and Co(AC)₂-doped CsPbBr₃ quantum dots as emitting layers to test the advantages of enhanced photoluminescence(PL),and analyzed the reasons for LED device performance optimization.