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The present work reports highly efficient flexible and reabsorption-free scintillators based on two zero-dimensional (0D) organic copper halides (TBA)CuX2 (TBA = tetrabutylammonium cation; X = Cl, Br). The (TBA)CuX2 exhibit highly luminescent green and sky-blue emissions peaked at 510 and 498 nm, with large Stokes shifts of 224 and 209 nm and high photoluminescence quantum yields (PLQYs) of 92.8% and 80.5% at room temperature for (TBA)CuCl2 and (TBA)CuBr2 single crystals (SCs), respectively. Interestingly, above room temperature, their PLQYs increase with temperature and reach near unity at 320 and 345 K for (TBA)CuCl2 and (TBA)CuBr2, respectively. The excellent properties originate from self-trapped excitons (STEs) in individual [CuX2]- quantum rods, which is demonstrated by the temperature-dependent PL, ultrafast transient absorption (TA) combined with density functional theory (DFT) calculations. The (TBA)CuX2 scintillators show bright radioluminescence (RL), impressive linear response to dose rate in a broad range, and high light yields. Their potential application in X-ray imaging is demonstrated by using (TBA)CuX2 composite scintillation screens. Importantly, flexible scintillators are demonstrated to be superior than flat ones for imaging nonplanar objects by conformally coating, which produce accurate images with negligible distortion.

Infrared solar cells (IRSCs) can supplement silicon or perovskite SCs to broaden the utilization of the solar spectrum. As an ideal infrared photovoltaic material, PbS colloidal quantum dots (CQDs) with tunable bandgaps can make good use of solar energy, especially the infrared region. However, as the QD size increases, the energy level shrinking and surface facet evolution makes us reconsider the matching charge extraction contacts and the QD passivation strategy. Herein, different to the traditional sol-gel ZnO layer, energy-level aligned ZnO thin film from a magnetron sputtering method is adopted for electron extraction. In addition, a modified hybrid ligand recipe is developed for the facet passivation of large size QDs. As a result, the champion IRSC delivers an open circuit voltage of 0.49 V and a power conversion efficiency (PCE) of 10.47% under AM1.5 full-spectrum illumination, and the certified PCE is over 10%. Especially the 1100 nm filtered efficiency achieves 1.23%. The obtained devices also show high storage stability. The present matched electron extraction and QD passivation strategies are expected to highly booster the IR conversion yield and promote the fast development of new conception QD optoelectronics.

Summary Defect sites are often proposed as key active sites in the design of catalysts. A promising strategy for improving activity is to achieve a high density of homogeneously dispersed atomic defects; however, this is seldom accomplished in metals. We hypothesize that vacancy-rich catalysts could be obtained through the synthesis of quantum dots (QDs) and their electrochemical reduction during the CO2 reduction reaction (CO2RR). Here, we report that QD-derived catalysts (QDDCs) with up to 20 vol % vacancies achieve record current densities of 16, 19, and 25 mAcm−2 with high faradic efficiencies in the electrosynthesis of formate, carbon monoxide, and ethylene at low potentials of –0.2, –0.3, and –0.9 V versus reversible hydrogen electrode (RHE), respectively. The materials are stable after 80 hr of CO2RR. These CO2RR performances in aqueous solution surpass those of previously reported catalysts by 2×. Together, X-ray absorption spectroscopy and computational studies reveal that the vacancies produce a local atomic and electronic structure that enhances CO2RR.

Solution-processed colloidal quantum dots (CQDs) are promising candidates for the third-generation photovoltaics due to their low cost and spectral tunability. The development of CQD solar cells mainly relies on high-quality CQD ink, smooth and dense film, and charge-extraction-favored device architectures. In particular, advances in the processing of CQDs are essential for high-quality QD solids. The phase transfer exchange (PTE), in contrast with traditional solid-state ligand exchange, has demonstrated to be the most promising approach for high-quality QD solids in terms of charge transport and defect passivation. As a result, the efficiencies of Pb chalcogenide CQD solar cells have been rapidly improved to 14.0%. In this review, the development of the PTE method is briefly reviewed for lead chalcogenide CQD ink preparation, film assembly, and device construction. Particularly, the key roles of lead halides and additional additives are emphasized for defect passivation and charge transport improvement. In the end, several potential directions for future research are proposed.

Colloidal quantum dots can be stabilized in either a polar solvent or a nonpolar solvent depending on their surface chemistry. The former is typically achieved by charge stabilization while the latter by steric hindrance. This allows reversible tuning of their surface polarity for targeted application by engineering their ligand profile. Here we developed a hybrid stabilization approach that leveraged a combination of steric hindrance and charge stabilization simultaneously. We demonstrated this mechanism in a phase transfer process where hexane dispersed and hydrophobic CdSe/CdS core/shell quantum dots were exchanged into the hydrophilic dimethylformamide (DMF) phase. This was achieved by employing both Z-type cadmium acetate and X-type halide ligands. The results suggested only by using this hybrid stabilization strategy were we able to achieve good colloidal stability while preserving their photoluminescence quantum yield. This hybrid ligand strategy may promise new opportunities for the application of QDs in optoelectronic areas.

Colloidal quantum dot (CQD) solar cells are solution-processed photovoltaics with broad spectral absorption tunability. Major advances in their efficiency have been made via improved CQD surface passivation and device architectures with enhanced charge carrier collection. Herein, we demonstrate a new strategy to improve further the passivation of CQDs starting from the solution phase. A cosolvent system is employed to tune the solvent polarity in order to achieve the solvation of methylammonium iodide (MAI) and the dispersion of hydrophobic PbS CQDs simultaneously in a homogeneous phase, otherwise not achieved in a single solvent. This process enables MAI to access the CQDs to confer improved passivation. This, in turn, allows for efficient charge extraction from a thicker photoactive layer device, leading to a certified solar cell power conversion efficiency of 10.6%, a new certified record in CQD photovoltaics.

A crosslinked hole-extracting electrical contact is reported, which simultaneously improves the stability and lowers the hysteresis of perovskite solar cells. Polymerizable monomers and crosslinking processes are developed to obviate in situ degradation of the under lying perovskite. The crosslinked material is band-aligned with perovskite. The required free carrier density is induced by a high-work-function metal oxide layer atop the device, following a remote-doping strategy.

The development of novel sodium-ion batteries has been hindered by the lack of ideal anode materials. Herein, we report both experimental and theoretical assessment of layered MoSe 2 nanoplates as the anode materials. The MoSe 2 nanoplates are successfully synthesized by a facile thermal-decomposition process. As the anode, the MoSe 2 nanoplates are capable of delivering the initial discharge and charge capacities of 513 and 440 mAh g −1 at the current of 0.1C in a voltage of 0.1–3 V, respectively. The analysis of Ex-situ XRD patterns reveals that there is no slippage between layers and the change of coordination of molybdenum when the MoSe 2 electrode is discharged to 0.6 V and conversion reactions during the following discharge/charge process are also demonstrated. In addition, the electronic structure, Na ions transport and conductivity are investigated by first-principles calculation. A quasi-2D energy favorable trajectory is proposed to illustrate the sodium ion vacancy-hopping migration mechanism form octahedron to tetrahedron in MoSe 2 lattice. The results suggest great potential of MoSe 2 as an anode material for Na ion batteries.

The real applications of Na3V2(PO4)3 cathode material for sodium batteries have been hindered by low-cost and facile synthesis method. Herein, we report a facile self-combustion method to synthesize Na3V2(PO4)3 nanoparticles coated with carbon shell (NVP/C). Using as the cathode, the NVP/C is capable of delivering the initial discharge and charge capacities of 100.72 and 111.3 mAh g−1 at the current of 0.1 C in a voltage of 2.5–3.8 V, and the capacity retention of the sample is approximately 95% of its initial specific capacity after 50th cycles. The first-principles simulation results show that the Na ions migration route prefers between two adjacent tetrahedral sites with the vacancy-hopping mechanism in a curved way, with the lowest activation energy of 0.292 eV. The diffusion coefficients DNa+ at room temperature was also calculated as higher as 2.38 × 10−9 cm2 s−1. The results suggest great potential of self-combustion synthesized NVP/C as cathode materials for Na-ion batteries.

A novel electrode material for sodium-ion batteries (NIBs), Na3V2(PO4)3 with a rhombohedral, Na+ superionic conductor (NASICON)-type structure, was synthesised via a solid-state carbon-thermal reduction reaction assisted by mechanochemical activation. Electron microscopy analysis showed that the synthesised Na3V2(PO4)3 particles had an average size of 300 nm, being coated with a uniform layer of carbon 3 nm in thickness. As a cathode material, Na3V2(PO4)3/C exhibited an initial specific discharge capacity of 98.17 mAh g−1 at 0.1C for potentials ranging from 2.5 to 3.8 V. This was owing to the V3+/V4+ redox couple, which corresponded to the two-phase transition between Na3V2(PO4)3 and NaV2(PO4)3. The cathode lost 4.92% of its discharge specific capacity after 50 cycles. As an anode material, Na3V2(PO4)3/C exhibited an initial specific discharge capacity of 63.2 mAh g−1 at 0.1C for potentials ranging from 1.0 to 2.5 V. This was owing to the V2+/V3+ redox couple, which corresponded to the two-phase transition between Na3V2(PO4)3 and Na4V2(PO4)3. The anode lost approximately 5.41% of its discharge specific capacity after 50 cycles. The three-dimensional channel structure of NaV2(PO4)3 and the changes induced in its lattice parameters during the charge/discharge processes were simulated on the basis of density functional theory.

CdSe magic-sized quantum dots (MSQDs) families 392 (F392) and 461 (F461) exhibiting bright band gap emission and little trap emission were synthesised via a non-injection one-pot approach, where cadmium acetate dihydrate (Cd(OAc) 2 ·2H 2 O) and selenium dioxide (SeO 2 ) were used as Cd and Se source compounds, respectively, and N-oleoylmorpholine was selected as reaction medium. The approach does not have to adding any long-chain fatty acid or phosphine ligands. The investigation showed that N-oleoylmorpholine played three roles of reaction medium, reductant of SeO 2 , and stabilizer of QDs. The reduction reaction step of SeO 2 to Se 0 was important to the regulation and control of the reactivity of Se precursors as well as the thermodynamic equilibrium between nucleation and dissociation of the nuclei. The parameters including the reaction temperature, Cd-to-Se feed molar ratio, and growth periods were investigated. The synthetic approach allowed long-term growth and stability of CdSe MSQDs in a wide range of temperature and Cd-to-Se feed molar ratios. Different families developed independently from different nuclei. The degree of supersaturation (DSS) impacted the presence of CdSe NCs with different sizes. The moderate DSS favored the common development of different species coexisting in the same batch, the relatively high DSS favored the long-term existence of CdSe MSQDs family with high thermodynamically stability. New growth protocol was proposed to explain the formation mechanism of CdSe MSQDs. The characterization of CdSe MSQDs by the transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) have been also accomplished.

High-quality CuInSe 2 nanoparticles were successfully synthesized through a green, simple, low-cost route using environmentally friendly N -oleoylmorpholine as a new solvent of Se powder and oleylamine as capping ligand. The as-synthesized nanoparticles were characterized by X-ray diffraction, TEM, HRTEM, and energy dispersive X-ray spectroscopy. The experimental results revealed that the as-prepared CuInSe 2 nanoparticles with chalcopyrite tetragonal structure have an average size about 8 nm. The facile and green synthesis strategy was also used to synthesize hexagonal shaped CuInSe 2 nanorings by altering the synthesis parameters. Possible shape evolution and crystals growth mechanisms have been suggested for the formation of spherical shaped CuInSe 2 nanoparticles and hexagonal shaped CuInSe 2 nanorings, respectively.

A bulk-heterojunction hybrid solar cell based on CdS quantum dots (QDs) as electron acceptor and P3HT as donor was fabricated for the first time. The CdS QDs synthesized by a one-pot method had good crystallinity and stability. The hybrid thin film of CdS-QDs and conjugated polymer was made by simple spin-coating deposition of CdS-QDs/P3HT composite solution on ITO substrates and then treated by bidentate ligand ethanedithiol. Under AM1.5G illumination, the power-conversion efficiency (PCE) of the thiol-treated monolayer film was more than three times higher than that of the untreated device. The hybrid solar cell based on the assembled trilayer blend film with ethanedithiol by a layer-by-layer approach exhibited a further improved PCE of 0.86%, which was sixfold higher than that of the thiol-treated monolayer device. The results can be explained via ethanedithiol effectively displacing the existing stearate ligands on the surface of QDs in situ and connecting nanoparticles by its end function group, shortening the interdot space and thus improving electron transport between the QDs. The morphology of the thiol-treated blend film was briefly investigated.

The latest advances in colloidal-quantum-dot material processing are combined with a double-sided junction architecture, which is done by efficiently incorporating indium ions in the ZnO eletrode. This platform allows the collection of all photogenerated carriers even at the maximum power point. The increased depletion width in the device facilitates full carrier collection, leading to a record 10.8% power conversion efficiency.

The high temperature oxide thermoelectric materials of p-type Ca 3 Co 4− x Ag x O 9 (denoted as p-Co349/Ag x ) and n-type Ca 1− y Sm y MnO 3 (denoted as n-Mn113/Sm y ) were prepared by the self-ignition method combined with a sintering technique. The influence of doping Ag and Sm on the thermoelectric properties of the corresponding materials was evaluated. The figures of merit, ZT, for the p-Co349/Ag 0.2 and n-Mn113/Sm 0.02 materials reached maxima of 0.20 and 0.15 at 973 K, respectively. The performances of thermoelectric devices constructed with the p- and n-type pairs were evaluated in terms of the maximum output power ( P max ) and manufacturing factor. The P max and volume power density for the four-leg devices reached 36.8 mW and 81.9 mW cm −3 at Δ T of 523 K, respectively.

A low-cost, green, and reproducibly non-injection one-pot synthesis of high-quality CdS quantum dots (QDs) is reported. The synthesis was performed in the open air by mixing precursors cadmium stearate and S powder into a new solvent N-oleoylmorpholine. An overlapped nucleation-growth stage followed by a dominated growth stage was observed. The resulting QDs exhibited well-resolved absorption fine substructure and a dominant band-edge emission with a narrow size distribution (the full width at half maximum (fwhm) was only 22-24nm). The maximum photoluminescence (PL) quantum yield (QY) was as high as 46.5%. Highly monodispersed CdS QDs with tunable sizes and similar PL fwhm and QYs could also be obtained from the CdS QDs in a large-scale synthesis. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs with high crystallinity had a cubic structure. A significant PL improvement and a continuous QY increase for the CdS QDs were observed during a long storage time in air and in a glovebox under room temperature. A slow surface reconstruction was proposed to be the cause for the PL enhancement of CdS QDs.

Two stable magic-sized CdSe families were simply and reproducibly synthesized at different growth temperature via a one-pot approach, in which N-oleoylmorpholine was used as reaction medium, and cadmium acetate dehydrate and Se powder as precursors. The pure 392 family obtained by surface passivation with either lauric acid or stearic acid at 150 °C exhibits strong white-light emission with a maximum quantum yield (QY) up to 27%. The broadband emission (370–680 nm), which is responsible for the white-light, is attributed to photoluminescence from both excitons and surface states. High-quality white-light emission can be stable for a long growth period (about 120 min) and at least a 2-month storage period. The high-resolution transmission electron microscopy (HRTEM) images verify the presence of the small size distribution and good crystallinity of the quantum dots (QDs) with a size range of 1.7–2.0 nm. X-ray diffraction (XRD) and selected area electron diffraction (SAED) confirm that the magic-sized CdSe QDs have a zincblende crystal structure. The energy-dispersed spectrometry (EDS) measurement indicates the as-prepared CdSe QDs have a cadmium-rich surface. The as-prepared CdSe QDs exhibit sharp and fixed absorption features and the white-light emitting from QDs can be retained for quite long reaction and storage periods.

The stearate-capped CdTe quantum dots (QDs) have been first prepared via direct reaction of cadmium stearate with Te powder in N-oleoylmorpholine solvent, which was a kind of clean, air-stable and conveniently synthesized acylamide, and can readily dissolve precursors cadmium stearate and Te powder at a relative low temperature. The as-prepared CdTe QDs exhibited size-dependent optical properties, steep absorbance edge and narrow photoluminescence full width at half maximum. The high-resolution transmission electron microscopy images and X-ray diffraction revealed that the highly monodisperse CdTe QDs were of regular spherical morphology with zinc blende crystal structure displaying mean sizes of about 4 nm. The energy dispersed spectrometry measurement indicated the presence of Cd and Te, with the Cd:Te ratio being close to 1:1. Fourier transform infrared transmission spectra confirmed the existence of stearate on the CdTe QDs surfaces. The experimental results also demonstrated that the stearate-capped CdTe QDs had an unexpected good stability.

Single-crystalline intrinsic and N-doped p-type ZnTe nanoribbons (NRs) were synthesized via the thermal evaporation method in argon-mixed hydrogen and nitrogen-mixed ammonia, respectively. Both intrinsic and doped ZnTe nanoribbons had zinc blende structure and uniform geometry. X-ray diffraction peaks of N-doped ZnTe nanoribbons had an obvious shift toward higher angle direction as compared with intrinsic ZnTe. X-ray photoelectron spectroscopy detection confirmed that the dopant content of nitrogen in ZnTe nanoribbons was close to 1%. Field-effect transistors based on both intrinsic and N-doped ZnTe nanoribbons were constructed. Electrical measurements demonstrated that N-doping led to a substantial enhancement in p-type conductivity of ZnTe nanoribbons with a high hole mobility of 1.2 cm−2 V−1 S−1 and a low resistivity of 0.14 Ω cm in contrast to the 6.2 × 10−3 cm−2 V−1 S−1 and 45.1 Ω cm for intrinsic nanoribbons. Moreover, the defect reaction mechanism was proposed to explain the p-type behaviors of bot...

Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic–inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

Ternarysemiconductor Zn 0.3 Cd 0.7 Te nanoribbons are, firstly, synthesized via a two-step process, and the structure characterizations reveal that the as-synthesized nanoribbons are single-crystalline with a zinc blende structure and a crystal growth direction of [1–10]. Nano-field-effect transistors are fabricated based on single nanoribbon, and the electron transport characteristics demonstrate that the Zn 0.3 Cd 0.7 Te ribbons have p-type conductivity with a mobility ( μ h ) of 5.7 cm 2 V −1 S −1 and carrier concentration ( n h ) about 1.1 × 10 17 cm −3 . The prepared nanoribbons with significant p-type conductivity will be a very attractive candidate for nanoelectronic devices.

Highly luminescent and quantum-yielding (QY) CdSe/ZnS core/shell quantum dots (CS QDs) were synthesised via a new succession route in a non-toxic solvent, N,N-Dimethyl-octadecyl-tertiary-amine(18DMA) at a mild temperature. The CS QDs were also proven to be as efficient in reaching high quantum yields (up to 74%) as their reported high-temperature synthesis with organic phosphine ligands. It was demonstrated that the synthesis temperatures directly determine the size by controlling the rate of the monomer diffusion and adsorption. It was also found that the amount of surfactant oleic acid determined the QY of the QDs, whereas it had little influence on the crystallisation.

Silicon based optoelectronic integration is restricted by its poor optoelectronic properties arising from the indirect band structure. Here, by combining silicon with another promising optoelectronic material, the CdS nanoribbon (NR), devices with heterojunction structure were constructed. The CdS NRs were also doped with gallium to improve their n-type conductivity. A host of nano-optoelectronic devices, including light emitting diodes, photovoltaic devices, and photodetectors, were successfully constructed on the basis of the CdS:Ga NR/Si heterojunctions. They all exhibited excellent device performances as regards high stability, high efficiency, and fast response speed. It is expected that the CdS NR/Si heterojunctions will have great potential for future applications of Si based optoelectronic integration.

Nanostructure arrays-based flexible devices have revolutionary impacts on the application of traditional semiconductor devices. Here, a one-step method to synthesize flexible ZnO nanostructure arrays on Zn-plated flexible substrate in Zn(NO3)2/NH3⋅H2Osolution system at 70–90∘Cwas developed. We found out that the decomposition of Zn(OH)2precipitations, formed in lowerNH3⋅H2Oconcentration, in the bulk solution facilitates the formation of flower-like structure. In higher temperature, 90∘C, ZnO nanoplate arrays were synthesized by the hydrolysis of zinc hydroxide. Highly dense ZnO nanoparticale layer formed by the reaction ofNH3⋅H2Owith Zn plating layer in the initial self-seed process could improve the vertical alignment of the nanowires arrays. The diameter of ZnO nanowire arrays, from 200 nm to 60 nm, could be effectively controlled by changing the stability of Zn(NH3)42+complex ions by varying the ratio of Zn(NO3)2toNH3⋅H2Owhich further influence the release rate ofZn2+ions. This is also conformed by different amounts of the Zn vacancy as determined by different UV emissions of the PL spectra in the range of 380–403 nm.

A low-intensity ultraviolet photodetector (PD), with a gain as high as ∼2.4 × 106, has been successfully constructed based on gallium (Ga) doped zinc sulfide (ZnS) nanoribbons (NRs). The device exhibits excellent photoconductive properties upon a bias voltage as low as ∼0.01 V in terms of high sensitivity to UV light with an intensity of 1 μW cm−2 (corresponding to an incident power of 10−14 W), relatively fast response times of ∼3.2 ms, and an extremely high detectivity of ∼1.3 × 1019 cm Hz1/2 W−1. The high gain and fast response time are attributed to the excellent ohmic contact obtained by using a high quality ITO electrode and having a carrier mobility as high as 130 cm2 V−1 s−1, which was confirmed from the back-gate field effect transistors. These results show that the single-crystalline n-type ZnS:Ga NRs will have potential applications in future high-performance low-intensity ultraviolet photodetectors.

Composition-controllable ternary CdSe(x)S(1-x) quantum dots (QDs) with multiple emission colors were obtained via a hot-injection-like method at a relatively low injection temperature (230 ° C) in octadecene. Then highly fluorescent CdSe(x)S(1-x)/ZnS core/shell (CS) QDs were synthesized by a facile single-molecular precursor approach. The fluorescent quantum yield of the resulting green (λ(em) = 523 nm), yellow (λ(em) = 565 nm) and red (λ(em) = 621 nm) emission of CS QDs in toluene reached up to 85%, 55% and 39%, respectively. Moreover, a QDs white light-emitting diode (QDs-WLED) was fabricated by hybridizing green-, yellow- and red-emitting CdSe(x)S(1-x)/ZnS CS QDs/epoxy composites on a blue InGaN chip. The resulting four-band RYGB QDs-WLED showed good performance with CIE-1931 coordinates of (0.4137, 0.3955), an R(a) of 81, and a T(c) of 3360 K at 30 mA, which indicated the combination of multiple-color QDs with high fluorescence QYs in LEDs as a promising approach to obtain warm WLEDs with good color rendering.