1：Experimental Design and Method Selection:

Temperature-dependent and time-resolved spectroscopy, diffuse reflectance spectroscopy, Raman scattering, DFT and MD calculations, and electrical characterizations were used to study perovskite single crystals and thin films with different A-site cations (Cs, FA, MA).

2：Sample Selection and Data Sources:

Single crystals of CsPbBr3, FAPbBr3, and MAPbBr3 were prepared using inverse temperature crystallization and modified methods. Polycrystalline thin films were prepared with varying precursor concentrations.

3：List of Experimental Equipment and Materials:

Equipment includes a regenerative amplifier (Coherent Libra), Ti-sapphire oscillator (Coherent Vitesse), spectrometer (Acton Spectra Pro 2500i), CCD (Princeton Instruments Pixis 400B), streak camera (Optronis Optoscope), cryostat (Janis), integrating sphere with UV-Vis-NIR spectrophotometer (Shimadzu UV-3600), Raman spectrometer (XY-Dilor), and VASP code for DFT/MD calculations. Materials include cesium bromide, lead bromide, DMF, acetonitrile, DMSO, GBL, formamidinium bromide, methylammonium bromide.

4：Experimental Procedures and Operational Workflow:

Crystals were grown, characterized by XRD and SEM, and subjected to PL, TRPL, diffuse reflectance, Raman, and EQE measurements at various temperatures and excitation conditions. DFT and MD simulations were performed to model lattice fluctuations.

5：Data Analysis Methods:

Data were analyzed using Voigt function fitting, non-negative matrix factorization for TRPL deconvolution, Debye relaxation model for Raman, and Saha ionization equation for carrier dynamics.