Effect of ligand exchange on the photoresponsivity of near-infrared sensors based on PbSe nanocrystals

The effect of ligand exchange was investigated on the optical and electrical characteristics of near-infrared sensors fabricated from PbSe nanocrystals. Different ligands such as oleic acid, ethanedithiol, and mercaptoacetic acid were used to cap the nanocrystals. The bandgap of the PbSe nanocrystals was measured using the optical absorption and tuned into the near-infrared region by controlling the growth time. The electrical properties of the sensors fabricated from the PbSe nanocrystals treated with different ligands were extracted by measuring the current-voltage characteristics. Furthermore, the optical properties of the different sensors were found by measuring the spectral response of each sensor.