Steady state photoinduced absorption of PbS quantum dots film

Abstract

We have measured steady state photoinduced absorption (PIA) of PbS quantum dot (QD) film in an energy range of interband electronic transitions at low temperature. PIA spectra show both positive and negative PIAs corresponding to five consecutive interband transitions. The close resemblance between PIA spectrum and the second derivative of the linear optical absorption strongly suggests that these steady state PIAs may be caused by photoinduced local electric field, i.e., the linear Stark effect. We postulate this local electric field be generated by the trapped charges under laser excitations. © 2008 American Institute of Physics.