Optical Properties Of Composite Structure Of Cesium Lead Bromine Perovskite And Gold Nanoparticles

Inorganic metal halide perovskite?Cs Pb X₃,X = Cl,Br,or I?nanocrystals?NCs?have received a lot of attention in the last few years due to their potential applications in light-emitting devices,such as LEDs and lasers.In particular,Cs Pb Br₃ NCs are attractive and of excellent light-emission characteristics,including a high photoluminescence quantum yield?PLQY?and narrow emission band width.However,high quantum efficiency is commonly dependent on post-synthesis treatment.Generally,their optical properties are strongly dependent on the chemical synthesis processes because of the strong correlation between the defects and the synthesis processes.Various strategies including removing intrinsic defects,metal ion doping have been developed.It is still necessary to find a simple and effective method for the preparation of Cs Pb Br₃ NCs with high emission efficiencies.In general,the absorption or luminescent properties can be modified by surface plasmon resonance?SPR?by metallic nanostructures.For instance,Au or Ag nanostructures coupled to luminescent semiconductor nanostructures?Zn O,Cd Se,Cd S etc.?can lead to the enhancement in luminescence efficiencies.Like other semiconductors,the emission efficiency of perovskite NCs can also be modified by SPR at the presence of Au or Ag nanostructures.The local SPR of mental nanostructures are often strongly influenced by the size,morphology,and distance.However,it is important to further understand the spacing effects on the coupling resonance.Here we report on a simple,single-step method for the in situ synthesis of Cs Pb Br₃ NCs with Au nanoparticles?Au NPs?.This method can efficiently improve the spontaneous formation of the hybrid of Au NPs and Cs Pb Br₃ NCs?Au@Cs Pb Br₃?.The optical properties of Cs Pb Br₃ NCs are found to be sensitive to the initial concentrations of Au NPs.High photoluminescence quantum yield?PLQY?of over 90% is obtained at optimal Au NP concentration.This excellent PL performance can be attributed to the SPR effect between the Cs Pb Br₃ NCs and the Au NPs,which is controllable by the spacing effect.Numerical simulations demonstrate that the contribution of individual Au NPs to the PL properties of Cs Pb Br₃ NCs depends on their sizes and spatial positions in a colloidal system.The emitted light from Cs Pb Br₃ NCs can achieve stronger and higher PLQY,due to coupling with the SP mode of Au NPs in proximity to Cs Pb Br₃ NCs,compared with those Cs Pb Br₃ NCs with embedded Au NPs.Finally,QLED devices with structure of ITO / PEDOT: PSS / Poly-TPD / TAPC / Au @ Cs Pb Br₃ / TPBi / Al were fabricated.Au@ Cs Pb Br₃ nanocrystals with high PLQY were used as the light emitting layer.As a result,the diode was successfully lit,and the device had good rectification characteristics.The electroluminescence brightness still needs to be improved,but these QLED were fabricated and characterized at ambient conditions.However,these experimental results have laid a good foundation for our subsequent work on QLED devices.