Hydroxypropylmethyl Cellulose Modified with Carbon Dots Exhibits Light-Responsive and Reversible Optical Switching.

A light-responsive optical switching material is reported, which was obtained by incorporating carbon dots (CDs) into thermochromic hydroxypropylmethyl cellulose (HPMC). The ultrasmall size of CDs guarantees the considerable transparency of CDs/HPMC. Under illumination, CDs/HPMC shows rapid and reversible optical switching between transparent and opaque states due to the remarkable photothermal effect of CDs.