High-Responsivity Vis–NIR Photodetector Based on a Ag₂S/CsPbBr₃ Heterojunction

Abstract

Quantum dots (QDs) have gained significant interest in optoelectronic devices due to their excellent properties. Single-QD materials limit the high performance of photodetectors (PDs). The performance of PDs is enhanced by combining two dissimilar materials to form a heterostructure. The high responsivity vis−NIR photodetector based on a Ag 2 S/CsPbBr 3 heterojunction is presented in this work. Using CsPbBr 3 QDs as the first absorption layer and Ag 2 S QDs as the second absorption layer, a bipolar carrier transporting channel was built. This layered arrangement can absorb light most effectively. The formation of a heterojunction promoted charge transfer and reduced the recombination of carriers, thus improving the performance of devices. The responsivity (R) is 11.3 A/W, and the specific detectivity (D*) is 3.55 × 10 10 Jones for the Ag 2 S/CsPbBr 3 PD under 405 nm irradiation. Meanwhile, the Ag 2 S/CsPbBr 3 heterojunction can absorb 350−1040 nm light, indicating that the device has a wide spectral detection capability (vis−NIR). The response time of the PD is 31/34 ms under 532 nm irradiation. This work provides a feasible way for high responsivity and zerodimensional heterojunction photodetectors.

Defect-Passivated Photosensor Based on Cesium Lead Bromide (CsPbBr3) Perovskite Quantum Dots for Microbial Detection

“…The CsPbBr 3 photosensors showed maximum photocurrent and critical parameter values at a specific wavelength in the range of 400–800 nm (541 nm for CsPbBr 3 /MoS 2 photosensor and 535 nm for CsPbBr 3 /MoS 2 with parylene-C photosensor). The maximum value of responsivity increased from 3.7 A/W to 6.1 A/W, the detectivity increased from 1.6 × 10 13 Jones to 3.4 × 10 13 Jones, and the EQE increased from 705.9% to 1392.1% after parylene-C coating under bias potential of 0.5 V. The analytical parameters from this and previous studies are summarized in Table . − Additionally, the responsivity and detectivity of the photosensor in this study were significantly higher than those of previously reported perovskite photosensors, as shown in Figure S6b.…”

Detecting Visible to Near-Infrared II Light via CsPbBr3 Nanocrystals/Y6 Heterojunctions

“…As shown in Figure 1b, the conduction band minimum (CBM) and valence band maximum (VBM) of CsPbBr 3 NCs are located at −3.6 eV and −5.9 eV, respectively. 27 The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of Y6 are at −4.1 eV and −5.6 eV. 21 When the two semiconductors make contact, a built-in electric field is created due to the difference in Fermi levels, thus forming a heterojunction, as shown in Figure 1c.…”

Compositional engineering of ZnBr2-doped CsPbBr3 perovskite nanocrystals: insights into structure transformation, optical performance, and charge-carrier dynamics

“…In eqn (1), Y, Y 1 , and Y 2 are amplitudes, t represents time, the short-lived decay component (t 1 ) corresponds to trapassisted recombination, and the long-lived decay component (t 2 ) corresponds to carrier recombination. 38,45,46 The average lifetime (t ave ) was computed using eqn (2). Decay-fitting parameters (Y 1 , Y 2 , t 1 , and t 2 ) and calculated average lifetimes (t ave ) of the decay curves are listed in Table S4 (ESI †).…”

“…Lead-halide perovskite nanocrystals (LHPNC) have been considered next-generation light-emitting semiconductors with promising applications in optoelectronics, such as photovoltaic cells, 1 photodetectors, 2 low-threshold lasers, 3 light-emitting diodes (LEDs) for solid-state lighting and display technologies, 4 anticounterfeiting, 5 sensors 6 and X-ray scintillators 7 because of their narrow PL, tunable bandgap, near unity photoluminescence quantum yield (PLQY), reduced fluorescent blinking, high defect tolerance, and efficient radiative recombination, which is achieved through the confinement of excitons in small sizes. 8 Significant advances have been made in the synthesis of LHPNCs using various techniques, which have enabled precise control of their composition, size, and shape to produce emission that spans the entire spectrum, from near-ultraviolet (UV) to near-infrared.…”