Photophoresis:
There is a known effect for levitating flat objects with two sides called photophoresis. This occurs when one of the sides absorbs lots of light and the other very little, creating a difference in temperature. Just like how temperature differences in the atmosphere cause winds, this temperature gradient makes molecules move in such a way as to create a lifting force on the object.
Benjamin Schafer at Harvard University in Massachusetts and his colleagues designed a device that could use photophoresis to levitate small atmospheric sensors that wouldn’t need motors or batteries to stay aloft. [“Weather sensors could float forever in the stratosphere using sunlight,” Karmela Padavic-Callaghan, NewScientist (29 October 2022, paywall)]
