Surface Engineering of Quantum Dots for Remarkably High Detectivity Photodetectors

Abstract

Ternary alloyed CdSe Te colloidal QDs trap-passivated by iodide-based ligands (TBAI) are developed as building blocks for UV-NIR photodetectors. Both the few surface traps and high loading of QDs are obtained by in situ ligand exchange with TBAI. The device is sensitive to a broad wavelength range covering the UV-NIR region (300-850 nm), showing an excellent photoresponsivity of 53 mA/W, a fast response time of ≪0.02s, and remarkably high detectivity values of 8 × 10 Jones at 450 nm and 1 × 10 Jones at 800 nm without an external bias voltage. Such performance is superior to what has been reported earlier for QD-based photodetectors. The photodetector exhibits excellent stability, keeping 98% of photoelectric responsivity after 2 months of illumination in air even without encapsulation. In addition, the semitransparent device is successfully fabricated using a Ag nanowires/polyimide transparent substrate. Such self-powered photodetectors with fast response speed and a stable, broad-band response are expected to function under a broad range of environmental conditions.

Double Active Layers Constructed with Halide Perovskite and Quantum Dots for Broadband Photodetection

“…The V TFL values of CISe QD film and perovskite film are 0.68 and 0.14 V, respectively. Herein, the n trap can be expressed by the following formula [ 23–27 ] here, ε is the relative dielectric constant of CISe QDs or perovskite, ε 0 is the vacuum permittivity, e is the elementary charge, and L is the thickness of the active film. The n trap of CISe QD film and perovskite film can be calculated as 4.0 × 10 16 and 2.7 × 10 16 cm −3 , respectively.…”

“…The current density downtrend of the device under 100 mW cm −2 is attributed to surface defects of QDs that would cause charge accumulation. [ 24,32 ] Different current densities of the devices under various light intensity indicate that the devices contain different light obligation. At the light power intensity of 100 mW cm −2 , the photocurrent of DALPD is 2.5 times that of the perovskite device (Figure 4b), which shows that DALPD has stronger optical sensitivity.…”

Enhanced-performance of self-powered flexible quantum dot photodetectors by a double hole transport layer structure

“…The lower dark current will also result in a faster response speed and high detectivity. 32,33 Responsivity (R) is a measure of the current output per optical input and is a key factor that determines the device sensitivity. 34,35 From Figure 2c, the responsivities of the double HTL-based device for excitation at wavelengths of 350 nm, 450 nm and 800 nm at a power of 100 mW/cm 2 are 37.0, 41.5 and 10.5 mA/W, respectively, which are 1.8, 4.0 and 3.5 times larger than those of the single HTL-based device.…”

Highly Responsive Ultraviolet Sensor Based on ZnS Quantum Dot Solid with Enhanced Photocurrent

“…UV-photodetectors received great scientific attention owing to their significant commercial applications including water treatment, defense safety 1 , flame detection, and space communication 2–5 . The commercially used silicon-based photodetector faces a major problem of low photon absorption capability in the Ultraviolet (UV) region due to its high reflection co-efficient 6 .…”