1：Experimental Design and Method Selection:

The study involved fabricating free-standing flexible PVA films with photoluminescent carbon quantum dots embedded in them and dispersing silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence were investigated.

2：Sample Selection and Data Sources:

The samples were prepared by mixing CDs and PVA solutions, then drying to form films. Silica microspheres with different diameters were dispersed on the surfaces of these films by spin coating.

3：List of Experimental Equipment and Materials:

A homemade microscope equipped with a high sensitivity fluorescence spectrometer was used for PL measurements. SEM was used to examine the morphologies of the dispersed microspheres. UV-Vis spectrometer and spectrofluorophotometer were used for absorption and PL measurements, respectively.

4：Experimental Procedures and Operational Workflow:

The fabrication process included preparing CDs and PVA solutions, mixing them, transferring to a petri dish, drying to form films, and then dispersing silica microspheres on the surfaces by spin coating. PL spectra were measured with a homemade setup.

5：Data Analysis Methods:

The PL enhancements were analyzed based on the measured spectra. The effects of microspheres on the near-field distribution of electric field were analyzed with the FDTD method.