1：Experimental Design and Method Selection:

The synthesis of CH3NH3PbX3 perovskite quantum dots was conducted at room temperature in the open air using short-chain C4H9NH3X as the capping agent. The morphology of CH3NH3PbBr3 thin films was improved by spin-coating a solution of CH3NH3Br, C4H9NH3Br, and PbBr2 in N, N-dimerthylformamide.

2：Sample Selection and Data Sources:

Materials used include PbCl2, PbBr2, PbI2, methylamine, butylamine, HCl, HBr, HI, N, N-dimerthylformamide, dimethylsulfoxide, and toluene.

3：List of Experimental Equipment and Materials:

UV-vis absorption spectra were recorded by Metash 5200 spectrophotometer. Photoluminescence spectra were measured using Shimadzu RF 5301PC. The relative photoluminescence quantum yields were obtained by comparing the integrated emission of the QD samples with a standard fluorescence dye.

4：Experimental Procedures and Operational Workflow:

The synthesis process involved dissolving CH3NH3Br and PbBr2 in DMF, adding C4H9NH3Br, and then dropping the precursor solution into toluene under vigorous stirring to form quantum dots. Thin films were fabricated by spin-coating the precursor solution on soda lime glass substrates followed by sintering at 90°C in air.

5：Data Analysis Methods:

The luminescence decay curve was programmed from a Lecroy Wave Runner 6100 digital oscilloscope using a tunable laser as the excitation source. The temperature dependent PL spectra were collected by a Maya 2000 Pro CCD-based fiber optic spectrometer.