PbS Materials Research Articles

Strategies to advance thermoelectric performance of PbSe and PbS materials

Strategies to advance thermoelectric performance of PbSe and PbS materials

Realizing thermoelectric cooling and power generation in N-type PbS0.6Se0.4 via lattice plainification and interstitial doping

Thermoelectrics have great potential for use in waste heat recovery to improve energy utilization. Moreover, serving as a solid-state heat pump, they have found practical application in cooling electronic products. Nevertheless, the scarcity of commercial Bi2Te3 raw materials has impeded the sustainable and widespread application of thermoelectric technology. In this study, we developed a low-cost and earth-abundant PbS compound with impressive thermoelectric performance. The optimized n-type PbS material achieved a record-high room temperature ZT of 0.64 in this system. Additionally, the first thermoelectric cooling device based on n-type PbS was fabricated, which exhibits a remarkable cooling temperature difference of ~36.9 K at room temperature. Meanwhile, the power generation efficiency of a single-leg device employing our n-type PbS material reaches ~8%, showing significant potential in harvesting waste heat into valuable electrical power. This study demonstrates the feasibility of sustainable n-type PbS as a viable alternative to commercial Bi2Te3, thereby extending the application of thermoelectrics.

Three-in-one novel flame retardant through grafting organophosphorus onto Fe-MOF functionalized Mg(OH)2 for improving fire safety and mechanical properties of PBS composites

As one typically sustainable polymer material, poly(butylene succinate) (PBS) is highly necessary to improve its flame retardancy and simultaneously maintain satisfied mechanical performances. In this study, “three-in-one” novel flame retardant was synthesized through grafting organophosphorus onto Fe-MOF functionalized Mg(OH)2 (labeled as MH@Fe-MOF-P), then it was introduced into PBS matrix to investigate its effect on flame retardancy and mechanical properties. The results indicated that PBS/20MH@Fe-MOF-P exhibited excellent flame retardancy, including that the LOI was 29.6%, the UL-94 rating reached to V0, and the peak of heat release rate (PHRR) decreased by 82.1%. The flame retardant mechanism was ascribed to the synergistic effect of Mg(OH)2, Fe-MOF and organophosphorus on delaying the decomposition and catalyzing the carbonization of PBS. Meanwhile, PBS/20MH@Fe-MOF-P presented better mechanical performances than PBS/20MH and PBS/20MH@Fe-MOF composites, resulting from the special structure of MH@Fe-MOF-P to achieve good dispersion of fillers and strong polymer-filler interface adhesion. This work provides a novel strategy to modify Mg(OH)2 with high flame retardant efficiency, and also broadens the practical applications of PBS materials with balanced comprehensive performances.

Exceptional PbS/CsPbCl3 heterostructure based on the structural, electronic and optical properties of PbS/CsPbX3(X=Cl, Br, I)

The construction of heterojunction between NIR photoelectric materials and other types of materials has the potential to improve the performance of VIS-NIR photoelectric materials and broaden the absorption spectrum. In this study, the properties and theoretical calculations are carried out using the near-infrared photoelectric material PbS and the perovskite material CsPbX3 (X = Cl, Br, I) to build heterostructures. The appropriate lattice mismatch rates (4.5 %, 2 % and 4.6 %) between PbS and CsPbX3 (X = Cl, Br, I) ensure the feasibility of constructing PbS/CsPbX3 (X = Cl, Br, I) heterogeneous structures. The electronic properties calculations revealed physical mechanisms that improve luminous efficiency. Notably, the I-type band alignment (-5.02eV < PbS < −3.77eV, −5.85eV < CsPbX3 (X = Cl, Br, I) < -3.35eV) at the PbS/CsPbX3 (X = Cl, Br, I) interface facilitates efficient electron and hole transfer from the CsPbX3 (X = Cl, Br, I) quantum dots to the PbS material, which was further validated by the observed difference in charge density. Among them, the electron cloud of PbS/CsPbCl3 heterostructure is more obvious, and the charge transfer ability is better than that of the other two heterostructures. The heterostructures extend the light absorption range of CsPbX3 (X = Cl, Br, I) from visible to near-infrared under the influence of PbS. By comparing the light absorption functions, it is found that PbS/CsPbI3> PbS/CsPbCl3> PbS/CsPbBr3 in this range. Regarding comprehensive stability, charge density transfer, and optical properties, PbS/CsPbCl3 has the best performance. Under the premise of ensuring stability, different light absorption characteristics can be achieved by adjusting the composition of halogen atoms in PbS/CsPbCl3. This study provides a theoretical basis for enhancing the performance of the PbS/CsPbX3 (X = Cl, Br, I) heterostructures in VIS-NIR optoelectronic materials through investigations of their electronic and optical properties. It yields a promising approach for the design of high-performance VIS-NIR heterogeneous materials.

Modeling and property study of thermoelectric converter based on subwavelength photothermal absorption structure

Achieving light absorption and conversion in a wide wavelength region and large angles of incidence is an effective way to improve the efficiency of thermoelectric devices. In this work, the thermoelectric converter device with a sub-wavelength photothermal absorption structure is designed, and the thermoelectric device is adapted to medium and high-temperature working environments by introducing PbS and SiGe thermoelectric materials. By changing the material of the surface heat-absorbing layer and studying the adjustment effect of the shape and size of the sub-wavelength photothermal absorption structure on reflectivity, the perfect absorption of sunlight with a wide wavelength region and large angles of incidence is realized, and the maximum photothermal conversion is achieved. Furthermore, the qualitative and quantitative relationships between the thermal absorption and thermoelectric conversion performance of PbS and SiGe thermoelectric materials and the physical parameters of surface subwavelength photothermal absorption structures are studied, so as to maximize the absorption and conversion of thermal energy into electrical energy. This work provides research ideas for the design of perfect thermoelectric devices.

Frustrated microstructures composite PbS material’s size perspective from XRD by variant models of Williamson–Hall plot method

Frustrated microstructures composite PbS material’s size perspective from XRD by variant models of Williamson–Hall plot method

Lead sulfide quantum dot assembly with biocompatible mechanical property and tunable hydrophilicity

The outstanding optical and electronic properties of lead sulfide (PbS) colloidal quantum dots have broad applications in nanotechnology. They are composed of an inorganic semiconductor core and organic ligands. Here, using 2,3-dimercaptosuccinic acid (DMSA) as a reactant, we synthesized PbS nanoparticles and assembled them on a pigeon feather substrate through a self-assembled monolayer process. This assembly process results in a significantly higher increase in the modulus and hardness of the synthesized PbS material compared to that of the PbS materials reported previously. Particularly, there is only a slight increase in the mechanical properties of the PbS layer compared with the bio-template, indicating the compatibility between the coating and base material, demonstrating its potential for biological applications, such as wearable flexible electronic devices. In addition, the DMSA of the rich carboxylic groups as a passivator promoted the tunability of the PbS surface from hydrophilic to superhydrophilic. The influence of the surface roughness of the PbS layer on the wetting behavior conforms to the Cassie–Baxter model.

Technology CAD (TCAD) Simulations of Mg2Si/Si Heterojunction Photodetector Based on the Thickness Effect.

Research on infrared detectors has been widely reported in the literature. For infrared detectors, PbS, InGaAs, PbSe, InSb, and HgxCd1-xTe materials are the most widely used and have been explored for photodetection applications. However, these are toxic and harmful substances which are not conducive to the sustainable development of infrared detectors and are not eco-friendly. Mg2Si is a green, healthy, and sustainable semiconductor material that has the potential to replace these toxic and damaging photoelectric materials, making photoelectric detectors (PDs) green, healthy, and sustainable. In this work, we report on the results of our simulation studies on the PN junction Mg2Si/Si heterojunction PD. A model structure of Mg2Si/Si heterojunction PD has been built. The effects of Mg2Si and Si layer thickness on the optical and electrical performance of Mg2Si/Si heterojunction PD are discussed. For the purpose of this analysis, we consider electrical performance parameters such as I–V curve, external quantum efficiency (EQE), responsivity, noise equivalent power (NEP), detectivity, on-off ratio, response time, and recovery time. The simulation results show that the Mg2Si/Si heterojunction PD shows optimum performance when the thickness of Si and Mg2Si layers are 300 nm and 280 nm, respectively. For the optimized structure, the reverse breakdown voltage was found to be −23.61 V, the forward conduction voltage was 0.51 V, the dark current was 5.58 × 10−13 A, and the EQE was 88.98%. The responsivity was found to be 0.437 A/W, the NEP was 6.38 × 10−12 WHz1/2, and the detectivity was 1.567 × 1011 Jones. With the on-off ratio of 1566, the response time was found to be 0.76 ns and the recovery time was 5.75 ns. The EQE and responsivity peak wavelength of PD show a redshift as the thickness of Mg2Si increases. The Mg2Si heterojunction PD can effectively detect infrared light in the wavelength range of 400 to 1400 nm. The simulation results can be utilized to drive the development of green Mg2Si/Si heterojunction PD in the future.

Solution Phase Growth and Ion Exchange in Microassemblies of Lead Chalcogenide Nanoparticles.

We demonstrate the synthesis of micron-sized assemblies of lead chalcogenide nanoparticles with controlled morphology, crystallinity, and composition through a facile room-temperature solution phase reaction. The amine–thiol solvent system enables this synthesis with a unique oriented attachment growth mechanism of nanoparticles occurring on the time scale of the reaction itself, forming single-crystalline microcubes of PbS, PbSe, and PbTe materials. Increasing the rate of reaction by changing reaction parameters further allows disturbing the oriented attachment mechanism, which results in polycrystalline microassemblies with uniform spherical morphologies. Along with polycrystallinity, due to the differences in reactivities of each chalcogen in the solution, a different extent of hollow-core nature is observed in these microparticles. Similar to morphologies, the composition of such microparticles can be altered through very simplistic room-temperature solution phase coprecipitation, as well as ion-exchange reactions. While coprecipitation reactions are successful in synthesizing core–shell microstructures of PbSe–PbTe materials, the use of solution phase ion-exchange reaction allows for the exchange of not only Te with Se but also Ag with Pb inside the core of the PbTe microparticles. Despite exchanging one Pb with two Ag cations, the hollow-core nature of particles aids in the retention of the original uniform microparticle morphology.

Preparation of poly(butylene succinate) vitrimer with thermal shape stability via transesterification reaction

AbstractPoly(butylene succinate) (PBS) refers to a high‐performance biodegradable polymer employed to substitute petroleum polymers that cause environmental issues. However, PBS exhibits the defect of flowing above the melting point and rapid dripping for its poor melt strength. Accordingly, this study proposed a novel method to fabricate PBS vitrimer by exploiting reactive extrusion technology to mix diepoxide with PBS and then by employing zinc acetate as a catalyst to crosslink the PBS. Therefore, after the reaction extrusion blending, the blend still has a lower viscosity and high processing performance; in the subsequent curing process, the polymer undergoes a transesterification reaction and the viscosity increases. Via transesterification to form a cross‐linked network, the storage modulus, and loss modulus of PBS vitrimer at 140°C reach 55,800% and 3500% of pure PBS, respectively. At this time, the crystallinity of PBS vitrimer is still as high as 56.9% (The crystallinity of pure PBS is 47.4%). And the shape stability of PBS at high temperatures was significantly improved. Moreover, PBS vitrimer could still be reshaped after the cross‐linking process. This study proposed a facile method to produce PBS materials exhibiting high thermal shape stability.

Quasi-zero-dimensional structure based photoelectronics

The architecture and main parameters of photosensor structures and devices based on colloidal quantum dots (CQDs) of II, IV and VI group elements of the Periodic Table of D. Mendeleev are considered. Hybrid structural schemes of photoresistor, photodiode and phototransistor with absorbing layers based on HgTe, HgSe, PbS, PbSe CQDs and 2D materials for operation in various spectral ranges are com-prehensively discussed.

Enhanced thermoelectric performance of hot-press Bi-doped n-type polycrystalline PbS

Lead sulfide (PbS) is a type of promising thermoelectric materials which is consist of elements with high natural abundance. However, the relatively low conversion efficiency limits its further application due to the high lattice thermal conductivity of PbS compared with that of PbTe. It has been widely accepted that nanostructuring and doping are effective ways to enhance the thermoelectric properties. Herein, nano/micro structure Bi doped PbS materials have beensynthesized by a facile method of hydrothermal synthesis. The nano/micro structure material systems exist abundant interface which could scatter mid- and low-frequency phonons effectively, combined with point defect such as Bi–Pb scattering high-frequency phonons, and thus the results show that the lattice thermal conductivity of PbS decreases with the increasing concentration of Bi3+ doping as expected. Moreover, the optimal power factor (PF) can be obtained by tuning the carrier concentration and mobility at the same time. The optimal thermoelectric figure of merit (ZT) can reach 0.89 for Pb0.96Bi0.04S at 773K and rises with the increase of the temperature without sign of saturation. Our work may shed light to further possible and environmentally friendly application of PbS-based thermoelectric materials.

Density functional theory investigation on formation of nanoscale PbS materials and its fabrication in silica optical fiber via atomic layer deposition

The formation mechanisms for lead sulfide (PbS) semiconductor nanomaterials grown on silica substrate were investigated using density functional theory. There are two main reaction processes for the adsorption of Pb(tmhd)2 on a silica substrate and the reaction with H2S to form PbS. The activation barriers of the two reaction processes were quite low at 10.1923 and 20.6778 kcal/mol, which is energetically favorable for PbS deposition by atomic layer deposition (ALD). In addition, PbS nanomaterials were introduced both on silica substrate and into the core of the silica fiber via ALD, with Pb(tmhd)2 and H2S as precursors. The structural properties of the PbS nanomaterials and optical properties of the PbS-doped fiber were characterized. There were obvious absorption peaks at 480, 695, and 1043 nm. The fiber exhibited photoluminescence at 1060–1370 nm with 1064 nm pumping. A gain of 9.4 dB was obtained at 1310 nm, which can be attributed to the PbS nanomaterials in the fiber core. This is crucial for optical fiber communications.

Lead Sulfide Saturable Absorber Based Passively Mode-Locked Tm-Doped Fiber Laser

In this paper, a passively mode-locked Tm-doped fiber laser by employing lead sulfide (PbS) nanoparticles as the saturable absorber (SA) is successfully demonstrated in the 2 μm region for the first time, to the best of our knowledge. Measured by a home-made balanced twin-detector setup at 2 μm, the PbS SA was characterized by the modulation depth of 10.69%, the non-saturable loss of 74.27%, and the saturable peak intensity of 8.62 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively. The laser delivered stable conventional soliton with a pulse duration of 1.24 ps and a repetition rate of 21.93 MHz. The center wavelength and 3 dB bandwidth are 1957.37 nm and 3.43 nm, respectively. Additionally, the second-order harmonic soliton pulses with a repetition rate of 43.86 MHz were also observed by further increasing the pump power. Our work reveals that PbS material is a reliable SA applied for pulse generation in the 2 μm spectral region.

Preparation of PBS and CaCO3 Composite Degradable Materials based on Melt Blending

Poly (butylene succinate)(PBS)/Calcium carbonate (CaCO3) composite were prepared by melt blending, and studied the effect of different coupling agents, PBS and CaCO3 mass ratio and coupling agent for composite. The results showed that aluminum acid coupling agent for the properties of composite materials improved the most obviously effect; with CaCO3 content increased, the degradation properties and tensile strength of composite materials rose, the impact strength and elongation at break decreased. With aluminum acid content increased, the tensile propeties and impact strength increased and then stabilization but no influence on degradation. When the PBS and CaCO3 mass ratio was 7:3, the coupling agent in an amount of 1.5%, the performance of PBS/CaCO3composite was better, meeting the basic requirements. Compared with pure PBS, it reduced the cost of nearly 30%, and application further.

Study on the application of the narrow distribution and controlled molecular weight hindered amine lighter stabilizers in poly(butylene succinate)

A series of hindered amine light stabilizer (HALS) with controlled molecular weight and narrow distribution was synthesized by reversible addition-fragmentation chain transfer(RAFT) polymerization, and its application in poly (butylene succinate) (PBS) was studied through accelerated aging experiments. The effects of different molecular weight light stabilizers on the degradation of PBS were studied. The aging degree and mechanism of PBS were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and mechanical properties testing. The extraction experiment was also carried out to study the migration of light stabilizers in PBS. Finally, the biodegradability test was conducted to study the effect of light stabilizers on biodegradation capability. The results showed that the hindered amine light stabilizer with high molecular weight can protect the PBS material to a great extent and reduce the photodegradation degree compared with the one with low molecular weight.

Lead Chalcogenide Nanoparticles and Their Size-Controlled Self-Assemblies for Thermoelectric and Photovoltaic Applications

We report a facile, room temperature synthesis of PbS, PbSe, PbSxSe1–x, and PbTe nanoparticles and their microscale assemblies by combining a chalcogen solution and a lead halide solution in select thiol–amine mixtures. Selection of an appropriate thiol–amine pair and/or the use of appropriate amine to thiol ratio has demonstrated a size control on nanoparticle self-assemblies ranging from nano- to microscale. Proper washing of these particles has yielded phase-pure and compositionally uniform material with minimal or no presence of any carbonaceous ligands on the particle surface, making it attractive for electronic device fabrication. The resulting PbS material exhibits bandgaps in the range 0.6 eV to as high as 1.2 eV for various assembly sizes. These optical bandgaps confirm the retention of quantum confinement of PbS material even in self-assembled nano/microstructures, which could be an interesting phenomenon for future photovoltaic development. Along with carbon-free, quantum-confined self-assemblies, this chemistry also provides a room temperature and instantaneous reaction route to synthesize individually dispersed PbS and PbSe particles with long chain ligand capping similar to traditional synthesis routes. The PbSe material synthesized from this route shows the ability to alloy with PbS at room temperature in the entire composition range and also demonstrates thermoelectric performance comparable to results in existing undoped PbSe literature.

Filter-Free Narrowband Photodetectors Employing Colloidal Quantum Dots

Tuning the electronic bandgap of quantum dots via the quantum size-effect enables the tailored spectral response of quantum dot photodetectors, light emitting diodes, and solar cells. Chemically synthesized colloidal quantum dot (CQD) provides an option to produce such quantum material in an inexpensive way. Here, we propose an approach to fabricate filter-free narrowband photodetectors in near-infrared and mid-infrared regions using PbS and HgSe CQD materials, respectively. The spectrally selective bandpass response is implemented by taking advantage of the carrier collection narrowing effect using a photodiode device architecture. Narrower bandpass response in near-infrared region is further achieved employing blended PbS CQDs with different sizes. The external quantum efficiency spectra of these CQD detectors are comprehensively studied using numerical calculation.

Bio-degradable material realization for antenna fabrication in wireless communications

The biodegradable PBS material is presented to be applied for microwave device design (antenna). The PBS is forming by using compression molding. The PBS thickness is 1 mm with the flexible characteristic. In this paper, the antenna design for the operating frequency band of 2400-2500 MHz is design using the bio-degradable material with the dielectric constant of 3.2. The prototype was fabricated. The characteristics of the proposed device were presented. The effected of the curved antenna and substrate are described in this work.

Tuning electronic and magnetic properties of V-, Cr-, and Mn-doped PbS via strain engineering: A first-principles proposal

We theoretically investigated the possibilities of establishing ferromagnetism and tailoring band gap of narrow-gap PbS with early 3d transition-metals (V, Cr, and Mn) doping and strain engineering. The results revealed that these magnetic impurities can be spontaneously incorporated into PbS matrix. Moreover, V- and Mn-doped PbS materials are magnetic insulators, while Cr-doped PbS becomes nearly half metallic. When taking the spin-orbit coupling (SOC) effect into account, the strong p-d hybridization gives rise to the band gap closing for V- and Mn-doped PbS, creating two novel spin-gapless semiconductors. The induced gapless state could be further modulated by external strain, resulting in a topological phase transition with both gap opening and band inversion for V- and Mn-doped PbS systems. Particularly, we find that V-doped PbS is a ferromagnetic compound with intrinsic exchange field, which may be a potential candidate for the realization of quantum anomalous Hall effect.