1：Experimental Design and Method Selection:

The study involved the preparation of CsPbBr3|Cs4PbBr6 composite thin films using thermal evaporation, with the ratio between CsPbBr3 and Cs4PbBr6 tuned by adjusting the ratio of CsBr and PbBr2 precursors.

2：3|Cs4PbBr6 composite thin films using thermal evaporation, with the ratio between CsPbBr3 and Cs4PbBr6 tuned by adjusting the ratio of CsBr and PbBr2 precursors. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Composite thin films were prepared on glass substrates, with the composition ratio varied to study its effects on optical and electrical properties.

3：List of Experimental Equipment and Materials:

Equipment included a thermal evaporation system, X-ray diffractometer, UV–vis–NIR spectrometer, integrating sphere spectrometer, atomic force microscopy, and LED device fabrication tools. Materials included CsBr, PbBr2, ITO-coated glass substrates, PEDOT:PSS, TPBi, LiF, and Al.

4：Experimental Procedures and Operational Workflow:

The process involved the thermal evaporation of precursors, annealing, device fabrication with various layers, and characterization of optical and electrical properties.

5：Data Analysis Methods:

Data analysis included measuring photoluminescence quantum yield, electroluminescence brightness, and device efficiency, as well as analyzing conductivity and morphology through AFM.