Ligand engineering of mid-infrared Ag2Se colloidal quantum dots

• Published in: Physica. E, Low-dimensional systems & nanostructures Vol. 124; p. 114223
• Main Authors: Hafiz, Shihab Bin, Al Mahfuz, Mohammad M., Scimeca, Michael R., Lee, Sunghwan, Oh, Soong Ju, Sahu, Ayaskanta, Ko, Dong-Kyun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2020
• Subjects: Colloidal quantum dots; Mid-infrared; Photodetectors; Responsivity; Surface ligands; Mid-infrared; Photodetectors; Colloidal quantum dots; Responsivity; Surface ligands
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2020.114223

Silver selenide colloidal quantum dots exhibit distinct optical absorption in the mid-wavelength infrared spectral region, which arises from the intraband transition between the first and the second quantum-confined energy levels. The optical absorption coefficient, carrier mobility, and carrier lifetime, which are the three primary parameters that determine the ultimate performance of a photodetector, are expected to be heavily dependent on the surface capping ligands. Herein, we characterize these parameters on silver selenide colloidal quantum dots films chemically treated with ligands selected from literatures that report high-performance quantum dot-based solar cells, photodetectors, transistors, and thermoelectrics. We correlate these results with the mid-infrared responsivities measured from photoconductive photodetectors fabricated from respective ligand-exchanged films. The insights gained from this study may serve as a foundation for enabling future intraband CQD-based MWIR sensing and imaging technologies. [Display omitted] •Reports the surface ligand engineering of recently discovered mid-infrared Ag2Se colloidal quantum dots.•Five ligands that report high-performance solar cells, photodetectors, transistors, and thermoelectrics are investigated.•Optoelectronic properties including optical absorbance, carrier mobility, and carrier lifetime are measured.•Photodetector performances are examined to gain an insight into the material property-device performance relationship.