Free Charges Produced by Carrier Multiplication in Strongly Coupled PbSe Quantum Dot Films

Abstract
We show that in films of strongly coupled PbSe quantum dots multiple electron–hole pairs can be efficiently produced by absorption of a single photon (carrier multiplication). Moreover, in these films carrier multiplication leads to the generation of free, highly mobile charge carriers rather than excitons. Using the time-resolved microwave conductivity technique, we observed the production of more than three electron–hole pairs upon absorption of a single highly energetic photon (5.7Eg). Free charge carriers produced via carrier multiplication are readily available for use in optoelectronic devices even without employing any complex donor/acceptor architecture or electric fields.