Improving the photoluminescence quantum efficiency of size-tunable, solution-processed lead-sulfide quantum dots in film

Lead-sulfide (PbS) nanocrystals have high photoluminescence quantum efficiency (PLQE) when synthesized in solution (30%). When those same nanocrystals are made into a film, the PLQE drops significantly. Since practical nanocrystal devices will employ nanocrystals in film, it is essential to improve their PLQE. It is also important to understand what factors influence the PLQE of nanocrystals in films.; This work shows that reducing the concentration of nanocrystals in polymer significantly improves the PLQE of polymer/nanocrystal films. It shows that forming films in the presence of an abundance of passivating organic molecules also results in a high PLQE. This work improves the PLQE of nanocrystals in film from less than 1% to above 10%.; This thesis also explores the effect of solvent, passivating ligand, pump intensity, and constant illumination on the PLQE of nanocrystals in film and solution.