Fig. 2.

Design of the energy landscape of a colloidal quantum dot infrared photodetector (CQDIP). a Scheme of the band structure of a CQDIP showing two mid-infrared intraband HgSe nanocrystals (NCs) embedded in a HgTe NC matrix. Important CQDIP structure parameters are highlighted in bold: the energy difference between HgSe 1P_e levels and HgTe conduction band (CB), as well as the average distance between two HgSe wells. b Infrared absorbance spectra of the four materials used for this study: HgSe NCs; HgTe NCs with band-edge at 3000 cm⁻¹ (HgTe 3k); HgTe NCs with band-edge at 4000 cm⁻¹ (HgTe 4k), and HgTe NCs with band-edge at 6000 cm⁻¹ (HgTe 6k). c Electronic spectra of the four materials used for this study, determined using a combination of X-ray photoelectron spectroscopic measurements and optical spectroscopy. Bandgap of each material is given in the x axis (intrabandgap is given for HgSe). Black dashed line is the Fermi level. d Energy difference $\Delta E=E_{\mathrm{CB}}\left(\mathrm{HgTe}\right)-E_{1{\mathrm{P}}_{\mathrm{e}}}\left(\mathrm{HgSe}\right)$ between HgSe 1P_e level and HgTe CB as a function of the HgTe NC bandgap, extracted from c. e Infrared absorption spectra of HgSe/HgTe 4k NC solutions. Fractions relates to the proportion of HgSe particles in the mix. f Estimation of the average distance ΔL between two HgSe NCs for a given HgSe fraction, assuming a close-packing organization. Horizontal error bars are determined using the error of NC size from transmission electron microscopy and determining the impact of these fluctuations of the HgSe/HgTe ratio. Vertical error bars are determined using the HgSe fraction error