Interfacial charge carrier dynamics of colloidal semiconductor nanoparticles

Understanding the dynamic properties of charge carriers at the liquid-semiconductor interface is critical to many applications including photocatalysis, solar energy conversion and photoelectrochemistry. Dynamic properties of charge carriers, including trapping, recombination, and transfer, in a number of semiconductor nanoparticle systems have been studied using powerful time-resolved laser techniques. Several interesting features have been identified, including exciton-exciton annihilation upon trap state saturation at high excitation intensities for CdS, CdSe, TiO2, ultrafast electron injection in dye sensitization of TiO2, increased transient absorption over transient bleach with increasing intensity for Ag2S and CuxS due to trap state saturation, surface dependence of electronic relaxation in PbI2 and BiI3, complex kinetics of the orange emission in Mn-doped ZnS, and surface-independent relaxation for Fe2O3 and PbS. These observations provide new insight into the interfacial charge carrier properties in colloidal semiconductor nanoparticles, which is important for designing novel nanoarchitectures for emerging technologies.