Energy Material Advances / 2021 / Article / Fig 2

Research Article

Intrinsic and Extrinsic Exciton Recombination Pathways in AgInS2 Colloidal Nanocrystals

Figure 2

(a) Normalized transient transmission spectrum of AgInS2 NCs collected at 5 ps after pumping at 2.3 eV in low fluence regime highlighting the A and B transitions, depicted here as shaded areas. Steady-state absorption spectrum for the same toluene solution of NCs used in TT measurements is reported as grey dashed line. The short green arrow shows the pumping energy. (b) Normalized bleaching kinetics for the A transition at 2.25 eV (green line) and for the B band at 1.9 eV (red line) after pumping close to the band-edge at 2.3 eV to avoid thermalization effects. The dashed line is a fit to an exponential rise function with 1.4 ps characteristic time. (c, d) Same as (a) and (b), but for pumping within the B transition band at 1.97 eV. A short red arrow shows the pumping energy. (e) Schematic diagram of the photophysical mechanism occurring at different pumping energies: slightly above the absorption shoulder at 2.3 eV (top panel) and within the B transition at 1.97 eV (bottom panel). Crossed thin vertical lines emphasize transition bleaching after the pump event. (f) MCD spectra at 6 T, at different temperatures (, 5, 10, 20 K). The dashed line is the absorption spectrum for the polymeric slab containing AgInS2 NCs used in MCD measurements. (g) MCD signal collected at 2.5 K showing linear trend with the magnetic field.