Exciton transfer dynamics between graphene quantum dots and MXene explored by transient absorption spectroscopy and its application.

Graphene quantum dots (GQDs) have considerable potential for use in optoelectronic applications due to their large surface area, excellent optical and electronic properties. There are zigzag edge, armchair edge emissions and amino group induced emission in the aminated GQDs. It can be also observed the stimulated emission and photoinduced absorption features of edge state and amino group from the transient absorption (TA) spectrum. In the presence of hole-rich TiCT MXene, the electrons in the GQDs can be trapped, inducing the photoluminescence (PL) quenching. The amino functional groups in GQDs would be decomposed by MXene, producing a defect emission. As the concentration of TiCT increases, the lifetime ratio R between the stimulated emission and photoinduced absorption features changes from -8.73 to -1.00 at 470 nm. A method based on the TA spectrum is proposed for detecting TiCT MXene with a sensitivity of 121.39 mL/mg, which is four times higher than that of PL quenching method.