1：Experimental Design and Method Selection:

A one-step antisolvent precipitation strategy was used to synthesize Cs4PbBr6/CsPbBr3 perovskite crystals, with CTAB added to restrict growth and form nanosheets.

2：Sample Selection and Data Sources:

Precursor solutions with specific molar ratios of CsBr, PbBr2, and CTAB in DMF were used, with toluene as an antisolvent.

3：List of Experimental Equipment and Materials:

Materials included PbBr2, CsBr, CTAB, DMF, and toluene. Instruments included X-ray diffractometer (X'pert PRO, PANalytical), SEM (Hitachi-S4800), TEM (FEI Technai G2 F20), AFM (Bruker Vecco and Oxford Cypher S), XPS (ESCALAB 250), fluorescence spectrometer (FLS920, Edinburgh Instruments), and integration sphere (cary-4000).

4：0). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Precursor solution was stirred, toluene was added to induce precipitation, and the product was washed and preserved. Characterization involved XRD, SEM, TEM, AFM, XPS, PL, PLE, and PLQY measurements.

5：Data Analysis Methods:

Data were analyzed using power-law dependence for excitonic nature, temperature-dependent radiative lifetime for dimensionality, and Arrhenius plot for activation energy.