1：Experimental Design and Method Selection:

Alcohol-assisted coprecipitation method was used to synthesize K2TiF6:Mn4+ (KTFM) microsheets (MSs). First-principles calculations were performed to study the synergistic effects of 1-propanol and HF on the growth of KTFM MSs.

2：Sample Selection and Data Sources:

KHF2, Ti[OCH(CH3)3]4, HF, and K2MnF6 were used as the K, Ti, F, and Mn sources, respectively. Different volumes of 1-propanol were added to guide the anisotropic growth of KTFM crystals.

3：List of Experimental Equipment and Materials:

X-ray diffraction (XRD, Bruker D2 phase diffractometer), scanning electron microscopy (SEM, FEI Quanta 400), transmission electron microscopy (TEM, Tecnai G2 F20), photoluminescence (PL) spectra (FluoroMax-3 spectrophotometer), temperature-dependent PL (THMS-600 heater), absolute PL quantum yield spectrometer (QY C11347, Hamamatsu), time-resolved and steady-state fluorescence spectrometer (Edinburgh FSL920), ICP-MS (Agilent Technologies 7700 series).

4：Experimental Procedures and Operational Workflow:

K2MnF6 and KHF2 were added to HF aqueous solution in an ice bath. A mixture of Ti(IV) isopropoxide and 1-propanol was added to the solution. The reaction proceeded under stirring, and the product was harvested by centrifugation, washed with acetone, and dried.

5：Data Analysis Methods:

XRD patterns were analyzed for phase identification. SEM and TEM were used for morphology and structure analysis. PL spectra were collected for emission characteristics. Quantum efficiency and thermal quenching were measured. DFT calculations were performed to understand the growth mechanism.