Fig. 1. Characterizations of morphology and photoelectrical properties of colloidal quantum dots^[30,32]. (a) TEM characterization image of colloidal quantum dots; (b) high-resolution transmission electron microscopy (HRTEM) characterization image of colloidal quantum dots, scale bar is 20 nm; (c) schematic diagram of synthesis method for colloidal quantum dots; (d) absorption spectra of colloidal quantum dots; (e) photoluminescence spectra of colloidal quantum dots with different wavelengths; (f) photoconductivity spectra of colloidal CdTe nanoparticle thin films with different sizes

Fig. 2. Schematic diagram of quantum dot energy level structure and schematic diagram of quantum dot synthesis process. (a) Energy level alignment of quantum dots with different heterostructures^[38]; (b) energy level structure of quantum dots; (c) energy absorption characteristics of different quantum dots^[39]; (d) schematic diagram of fabrication process for core-shell structured quantum dots^[39]; (e) schematic diagram of quantum dot device fabrication^[39]; (f) schematic diagram of single-dot quantum dot device testing setup^[39]

Fig. 3. Schematic diagram of bulk quantum dot coupling technology and its characterization^[48]. (a) Structure of dual-channel detector for visible and short-wave infrared detection; (b) schematic diagram of tunable Fermi level structure; (c) energy band diagram of quantum dot/graphene/silicon junction; (d) current-voltage (I-V) characteristics of quantum dot and graphene; (e) patterned quantum dot device fabricated via photolithography; (f) transmission curves of quantum dots with different filling factors

Fig. 4. Schematic diagram of planar coupling process case and its characterization^[49]. (a) Schematic diagram of fabricated three-pixel photodetector structure; (b) scanning electron microscope (SEM) image of tricolor planar-coupled device; (c) absorbance curves of different colloidal quantum dots; (d) patterned quantum dot thin film; (e) electrode array; (f) SEM image of device assembled with patterned quantum dot thin film

Fig. 5. Schematic diagram of hetero-bandgap quantum dot coupling process and its characterization^[50]. (a) Schematic diagram of “back-to-back” structure of dual-band quantum dot infrared detector; (b) cross-sectional SEM image of dual-band infrared detector; (c) atmospheric window absorption spectra and absorption curves of quantum dots; (d) energy band diagram of dual-band device; (e) schematic diagram of single-point scanning imaging system; (f) imaging results of dual-band system

Fig. 6. Schematic diagram of three-band hetero-bandgap quantum dot coupling process and its characterization^[51]. (a) Schematic structure of three-band quantum dot device; (b) cross-sectional SEM image of three-band infrared detector; (c) SEM image of colloidal quantum dots; (d) absorption spectra of quantum dots with different bandgaps; (e) schematic diagram of testing setup; (f) response peak curves under different bias voltages

Fig. 7. Schematic diagram of optical filter coupling process and its characterization^[52]. (a) Schematic diagram of low-cost, tunable hyperspectral sensor based on colloidal quantum dots; (b) spectral transmission peak as function of optical spacer thickness; (c) spectral transmission curves of distributed Bragg reflector filters with different SiO₂/Si layer counts; (d) measured spectral responsivity of fabricated colloidal quantum dots-based hyperspectral detector; (e) single-pixel hyperspectral imaging system; (f) short-wave hyperspectral image cubes of different solvents captured by detector

Fig. 8. Comparison of fabrication processes for focal plane arrays^[61]. (a) Schematic diagram of traditional infrared focal plane array fabrication process based on flip-chip bonding; (b) schematic diagram of direct integration process using colloidal quantum dots on 8-inch wafer

Fig. 9. Parameters and imaging images of colloidal quantum dot detectors^[62]. (a) NETD histogram of mid-wave colloidal quantum dot focal plane; (b) NETD distribution map; (c) J, QE, and NETD curves under different bias voltages; (d) power spectral density as a function of frequency; (e) imaging effect

Fig. 10. Short-wave colloidal quantum dot focal plane array and imaging instrument^[63]. (a) Photograph of focal plane device; (b) TEM characterization image of colloidal quantum dots; (c) absorption comparison between colloidal quantum dots and InGaAs materials; (d) schematic diagram of colloidal quantum dot device; (e) photograph of colloidal quantum dot camera; (f) schematic diagram of short-wave imaging using colloidal quantum dots

Fig. 11. Capture-type quantum dot detector^[61]. (a) Photograph of readout circuit wafer; (b) photograph of short-wave colloidal quantum dot device; (c) short-wave imaging effect; (d) schematic diagram of capture-type structure; (e) energy band diagram of capture-type structure; (f) comparison of dark current between capture-type photodetector and reference detector

Fig. 12. Parameters and imaging effects of colloidal quantum dot megapixel mid-wave devices^[64]. (a) Schematic structure of megapixel mid-wave device based on colloidal quantum dots; (b) photograph of colloidal quantum dot mid-wave focal plane array with a pixel size of 1280×1024; (c) response distribution and response histogram; (d) distribution of blind and overheated pixels in detector; (e) imaging effect

Fig. 13. Parameters and performance of direct photolithography ultraviolet-infrared detector^[67]. (a) Detector structure for UV and SWIR imaging fabricated by direct photolithography process; (b) schematic diagram of pixel unit structure using direct photolithography; (c) absorption spectra for SWIR and MWIR; (d) responsivity as a function of wavelength; (e) UV imaging result of the UV/SWIR detector; (f) short-wave imaging result of the UV/SWIR detector

Fig. 14. Effect diagram of ultra-broadband spectrum imaging instrument^[68]. (a) Schematic diagram of structure of ultra-broadband spectrum imaging instrument; (b) photograph of ultra-broadband imaging instrument (top) and SEM cross-sectional image (bottom); (c) Tuac diagram of PbS and HgTe CQDs with absorption wavelengths ranging from visible to MWIR regions; (d) schematic diagram of multispectral and ultra-broadband imaging setup for ultra-broadband spectrum imaging instrument; (e) effect diagram of multispectral imaging mode; (f) effect diagram of ultra-broadband spectrum imaging mode

Fig. 15. Schematic diagram of micro-spectrometer system based on colloidal quantum dots and detection spectral curves^[80]. (a) Filter-style configuration of colloidal quantum dot materials, with each dot representing a colloidal quantum dot filter; (b) transmittance spectral curves of selected colloidal quantum dots; (c) photograph of quantum dot micro-spectrometer; (d) reconstructed spectral band curves of quantum dot micro-spectrometer and reference spectral curves; (e) comparison between emission spectra of five colloidal quantum dot samples and their corresponding reference spectra

Fig. 16. Schematic diagram and measurement curves of near-infrared computational spectrometer spectral measurement device^[81]. (a) Schematic diagram of near-infrared spectral measurement system for computational spectrometer; (b) absorption curves of PbS quantum dots increasing with growth time; (c) schematic diagram of colloidal quantum dot filters; (d) comparison between reconstructed spectra and reference spectral curves