Carrier Density Modulation in PbSe Quantum Dot Films via In-Solution Ligand Exchange

In-solution ligand exchange of PbSe QDs is used to examine the effect of capping ligand on the carrier density of PbSe QD films. Results show that carrier density can be modulated by a factor of 5 by choice of ligand without any additional post deposition treatments. Proper fabrication and measurement conditions for calculating carrier densities from C-V measurements using a sandwich structure on P-doped Si/SiO2/Al2O3/QD/Au structure capacitance devices are outlined. Combining carrier density results with field-effect-transistor measurements, promising ligands which display lower carrier densities without having a significant drop off in carrier mobility are identified as candidates for photodetection purposes.