Electron and Hole Injection in PbSe Quantum Dot Films

Electrochemical methods are used to inject charge into films of colloidal semiconductor nanocrystals of PbSe. The injection of electrons and holes into quantum confined states is confirmed by monitoring changes in the IR absorption spectrum. Holes are injected into the 1Sh state, causing a bleach of the 1Sh−1Se and 1Sh−1Pe interband transitions and inducing a 1Sh−1Ph intraband absorption. Electrons can be sequentially injected into the 1Se and 1Pe states, first bleaching the 1Sh−1Se and 1Ph−1Se interband transitions and inducing a 1Se−1Pe intraband absorption, and then bleaching the 1Sh−1Pe transition and inducing a 1Pe−1De intraband absorption.