Electron and hole adducts formed in illuminated InP colloidal quantum dots studied by electron paramagnetic resonance.
An electron paramagnetic resonance (EPR) study of photoexcited colloidal InP quantum dots (QD) shows the formation of electron and hole adducts. An EPR signal at g = 0.58 is assigned to a nonradiative hole trap that does not form immediately upon illumination, but forms only after the illuminated sample ages and becomes stabilized at room temperature; it then becomes permanent at the InP QD surface. This signal completely disappears upon electron injection into the QD from a reducing agent (sodium biphenyl). Light immediately quenches the signal at g = 0.58, and it re-forms reversibly when the light is turned off.more »