- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Colloidal-Quantum-Dot-in-Perovskite Nanowires
摘要： Colloidal quantum dots are materials of interest in infrared detection – a consequence of their near-infrared light harvesting capability, tunable bandgap, and solution-processing. Herein we develop a quantum-dot-in-perovskite-nanowire consisting of PbS quantum dots embedded inside MAPbI3 nanowires. The kinetics of perovskite nanowire growth were tracked. We found that N, N-dimethylformamide induced the formation of perovskite nanowires, and that their growth was accelerated upon PbS quantum dot inclusion. We then used this nanocomposite to fabricate photodetectors that showed a light response from the visible to near infrared region up to 940 nm. Finally, a flexible photodetector was fabricated on a polyethylene terephthalate substrate.
关键词： MAPbI3 nanowires,flexible photodetector,PbS quantum dots
更新于2025-11-14 17:04:02
-
Enhanced Charge Transfer and Responsivity in Hybrid Quantum Dot/Graphene Photodetectors Using ZnO as Intermediate Electrona??Collecting Layer
摘要： Hybrid graphene (Gr)–quantum dot (QD) photodetectors have shown ultra-high photoresponsivity combining the strong light absorption of QDs with the high mobility of Gr. QDs absorb light and generate photocarriers that are efficiently transported by Gr. Typically, hybrid PbS–QD/graphene photodetectors operate by transferring photogenerated holes from the QDs to Gr while photoelectrons stay in the QDs inducing a photogating mechanism that achieves a responsivity of 6 × 107 A W?1. However, despite such high gain, these systems have poor charge collection with quantum efficiency below 25%. Herein, a ZnO intermediate layer (PbS-QD/ZnO/Gr) is introduced to improve charge collection by forming an effective p-n PbS-ZnO junction driving the electrons to the ZnO layer and then to Gr. This improves the photoresponsivity of the devices by nearly an order of magnitude with respect to devices without ZnO. Charge transfer to Gr is demonstrated by monitoring the change in Fermi level under illumination for conventional PbS-QD/Gr and for ZnO intermediate PbS-QD/ZnO/Gr devices. These results improve the capabilities of hybrid QD/Gr configurations for optoelectronic devices.
关键词： PbS quantum dots,graphene,optoelectronics,ZnO intermediate layers
更新于2025-09-23 15:21:01
-
Ultrahigh brightening of infrared PbS quantum dots via collective energy transfer induced by a metal-oxide plasmonic metastructure
摘要： We demonstrate a solution-processed heterojunction interface formed via addition of a thin buffer layer of CdSe/ZnS quantum dots to a functional metal oxide plasmonic metastructure (FMOP) can set up a collective inter-quantum dot energy transport process, significantly enhancing the emission of infrared PbS quantum dots. The FMOP includes a Schottky junction, formed via deposition of a Si layer on arrays of Au nanoantennas, and a Si/Al oxide charge barrier. We show when these two junctions are separated from each other by about 15 nm and the CdSe/ZnS quantum dot buffer layer is placed in touch with the Si/Al oxide junction, the quantum efficiency of an upper layer of PbS quantum dots can increase by about one order of magnitude. These results highlight a unique energy circuit formed via collective coupling of the CdSe/ZnS quantum dots with the hybridized states of plasmons and diffraction modes of the arrays (surface lattice resonances) and coupling between such resonances with PbS QDs via lattice-induced photonic modes.
关键词： exciton-plasmon coupling,plasmons,collective,PbS quantum dots,metallic nanoantennas,surface lattice resonances,energy transfer
更新于2025-09-23 15:19:57
-
Dynamic Ligand Surface Chemistry of Excited PbS Quantum Dots
摘要： The ligand shell around colloidal quantum dots mediates the electron and energy transfer processes that underpin their use in optoelectronic and photocatalytic applications. Here, we show that the surface chemistry of carboxylate anchoring groups of oleate ligands passivating PbS quantum dots undergoes significant changes when the quantum dots are excited to their excitonic states. We directly probe the changes of surface chemistry using time-resolved mid-infrared spectroscopy that records the evolution of the vibrational frequencies of carboxylate groups following excitation of the electronic states. The data reveal a reduction of the Pb?O coordination of carboxylate anchoring groups to lead atoms at the quantum dot surfaces. The dynamic surface chemistry of the ligands may increase their surface mobility in the excited state and enhance the ability of molecular species to penetrate the ligand shell to undergo energy and charge transfer processes that depend sensitively on distance.
关键词： surface chemistry,PbS quantum dots,ligand shell,colloidal quantum dots,time-resolved mid-infrared spectroscopy
更新于2025-09-19 17:13:59
-
Effect of Cu doping and swift heavy ion irradiation on PbS quantum dots and their applications in solar cells
摘要： Copper ions are incorporated into the PbS quantum dots as dopants via a chemical method and an ion irradiation method. For irradiating the samples, a 100?MeV copper swift heavy ion beam is used with three different doses of 1?×?1011, 3?×?1011, and 1?×?1012?ions/cm2. The doped and irradiated samples are characterised by different techniques and introduced as a sensitising layer in a solar cell. The current density–voltage characteristics of the solar cells are studied under white light illumination conditions and the solar cell parameters such as Jsc, Voc, fill factor, and efficiency are obtained. Efficiency as high as 4.78% is obtained for irradiated quantum dots, which is significantly higher than that of pristine and doped quantum dot solar cells. However, at higher ion dosage, the solar cell efficiency degrades due to unwanted particle agglomeration in quantum dots.
关键词： Cu doping,solar cells,swift heavy ion irradiation,PbS quantum dots
更新于2025-09-16 10:30:52
-
Observation of charge transfer in mixed-dimensional heterostructures formed by transition metal dichalcogenide monolayers and PbS quantum dots
摘要： We report an experimental study on charge transfer properties of mixed-dimensional heterostructures formed by zero-dimensional PbS quantum dots and two-dimensional transition metal dichalcogenides. Monolayers of MoSe2 and MoS2 were fabricated by mechanical exfoliation and chemical vapor deposition techniques, respectively. PbS quantum dots with diameters of 2.3 and 5 nm were synthesized by a hot-injection method and characterized by optical absorption spectroscopy and ultraviolet photoemission spectroscopy. The quantum dots were deposited on the MoS2 and MoSe2 monolayers to form heterostructures. Photoluminescence and transient absorption measurements were performed on the heterostructures as well as individual materials to reveal their photocarrier dynamics. We found that the holes excited in MoSe2 can efficiently transfer to both 2.3- and 5-nm PbS quantum dots, while electrons in these quantum dots cannot transfer to MoSe2. Similar charge transfer properties were observed between MoS2 and the 5-nm PbS quantum dots, while no charge transfer was observed between MoS2 and the 2.3-nm quantum dots. These results provide useful information for understanding the physical mechanism of charge transfer in mixed-dimensional heterostructures and for developing PbS quantum-dot-based mixed-dimensional materials.
关键词： PbS quantum dots,mixed-dimensional heterostructures,transition metal dichalcogenides,photocarrier dynamics,charge transfer
更新于2025-09-12 10:27:22
-
PbS quantum dot tandem solar cell based on solution-processed nanoparticle intermediate layer
摘要： Tandem cells are one of the most effective ways of breaking the single junction Shockley-Queisser limit. Solution-processable PbS quantum dots are good candidates for producing multiple junction solar cell due to their size-tunable bandgap. The intermediate recombination layer connecting the subcells in a tandem solar cell is crucial for device performance because it determines the charge recombination efficiency and electrical resistance. In this work, solution-processed ultra-thin NiO and Ag nanoparticle film serves as an intermediate layer to enhance the charge recombination efficiency in PbS QD dual-junction tandem solar cells. The champion devices with device architecture of ITO/S-ZnO/1.45 eV PbS-PbI2/PbS-EDT/NiO/Ag NP/ZnO NP/1.22 eV PbS-PbI2/PbS-EDT/Au delivers a 7.1% power conversion efficiency, which outperforms the optimized reference sub-cells. This result underscores the critical role of appropriate nanocrystalline recombination layer in producing high-performance solution-processed PbS QD tandem cells.
关键词： recombination layer,tandem solar cell,PbS quantum dots,complementary absorption,intermediate layer
更新于2025-09-12 10:27:22
-
Excitation-wavelength- and size-dependent photo-darkening and photo-brightening of photoluminescence from PbS quantum dots in glasses
摘要： PbS quantum dots (QDs) with mean radii of 3.7 nm to 9.0 nm are precipitated in silicate glasses. Upon above-band-gap excitation, photoluminescence from QDs is strongly dependent on their size and excitation wavelength, exhibiting photo-darkening (PD) or photo-brightening (PB). Photoluminescence of PbS QDs exhibits strong darkening by short excitation wavelength but the darkening gradually mitigated as the excitation wavelength increased and even turns to be photo-brightening at room temperature. But PD and PB show a much more complicated variation tendency under the same excitation condition when the size of QDs increased. The dependence of PD and PB on the QDs’ size and excitation wavelength indicates that electron/hole trap states of PbS QDs, defect states in surrounding glass matrix as well as on the interface between the glass matrix and PbS QDs all have strong effects on the photoluminescence properties of PbS QDs. These findings are important to modulate the photoluminescence and promote the potential applications of PbS QDs embedded glasses towards various optoelectronic devices.
关键词： photoluminescence,PbS quantum dots,photo-darkening,excitation wavelength,size-dependent,photo-brightening
更新于2025-09-12 10:27:22
-
Optoelectronic response of hybrid PbS-QD/graphene photodetectors
摘要： Lead sulfide quantum dots (QDs) have been widely used for various optoelectronic devices due to their high absorption coefficient and tunable bandgap. However, the low mobility of QD films results in poor charge collection and device performance. By combining QDs with graphene into hybrid graphene/QD photodetectors, photocarriers from QDs are transferred to graphene, improving charge collection and transport, drastically increasing the photoresponsivity. Herein, we carry a systematic analysis on how critical tuning parameters such as QD size and QD film thickness affect responsivity, spectral response, and time response. We report the absorption coefficient, refractive index (n, k), penetration depth, and energy bandgap of PbS QDs of different sizes. We study systematically how the photocurrent, photoresponsivity, time response, and power density dependence vary with QD size in hybrid Gr/QD. The bandgap of lead sulfide quantum dots was size-tuned between 0.86 and 1.39 eV. The time response shows that subsecond modulation can be achieved for different QD sizes with a responsivity up to 107 A/W at power densities of 10?5 mW/cm2. We also studied how the performance of the photodetectors is affected by the thickness, discussing the limitations on the thickness by the compromise between light absorption and charge collection. We describe how the optical response shifts toward the infrared as QD films get thicker. Time responses below 1 s are obtained for graphene/QD devices with thickness from 150 nm to 1 μm. This systematic study provides important guidelines to design hybrid graphene/QD photodetectors and tune their spectral response and performance.
关键词： hybrid devices,optoelectronic response,PbS quantum dots,photodetectors,graphene
更新于2025-09-12 10:27:22
-
Influence of PbS Quantum Dots-Doped TiO2 Nanotubes in TiO2 Film as an Electron Transport Layer for Enhanced Perovskite Solar Cell Performance
摘要： Lead sulfide quantum dots-doped titanium dioxide nanotubes (PbS QDs-doped TNTs) were successfully prepared by the hydrothermal and impregnation methods. A thin layer of titanium dioxide (TiO2) comprising of PbS QDs-doped TNTs was applied as an electron transport layer (ETL) in order to improve the planar perovskite solar cell efficiency. The role of incorporating a high surface area of one-dimensional nanotube structure of TiO2 in the conventional TiO2 layer provided a special unidirectional charge transport and a high charge collection. Moreover, doping PbS QDs onto the surface of TNTs modified the electronic and optical properties of the ETL by downshifting the conduction band of TiO2 from ?4.22 to ?4.58 eV, therefore promoting the driving force of an electron injection to the transparent conductive electrode. By varying the concentration of PbS QDs-doped TNTs dispersed in 2-butanol from 0.1 to 0.9 mg/mL, a concentration of 0.3 mg/mL PbS QDs-doped TNTs was the optimum concentration to be mixed with TiO2 solution for the ETL deposition. The best perovskite solar cell performance with the optimum loading of PbS QDs-doped TNTs provided 14.95% power conversion efficiency, which was increased from 12.82% obtained from the cell with pristine TiO2 film as ETL.
关键词： PbS quantum dots (PbS QDs),perovskite solar cells (PSCs),TiO2 nanotubes (TNTs),Electron transport layer (ETL)
更新于2025-09-11 14:15:04