We alloyed Zn
into CsPbI
perovskite nanocrystals by partial substitution of Pb
with Zn
, which does not change their crystalline phase. The resulting alloyed CsPb
Zn
I
nanocrystals exhibited an ...improved, close-to-unity photoluminescence quantum yield of 98.5% due to the increased radiative decay rate and the decreased non-radiative decay rate. They also showed an enhanced stability, which correlated with improved effective Goldschmidt tolerance factors, by the incorporation of Zn
ions with a smaller radius than the Pb
ions. Simultaneously, the nanocrystals switched from n-type (for CsPbI
) to nearly ambipolar for the alloyed nanoparticles. The hole injection barrier of electroluminescent LEDs was effectively eliminated by using alloyed CsPb
Zn
I
nanocrystals, and a high peak external quantum efficiency of 15.1% has been achieved.
Lead halide perovskites (LHPs) have received increased attention owing to their intriguing optoelectronic and photonic properties. However, the toxicity of lead and the lack of long-term stability ...are potential obstacles for the application of LHPs. Herein, the epitaxial synthesis of CsPbX
(X = Cl, Br, I) perovskite quantum dots (QDs) by surface chemical conversion of Cs
GeF
double perovskites with PbX
(X = Cl, Br, I) is reported. The experimental results show that the surface of the Cs
GeF
double perovskites is partially converted into CsPbX
perovskite QDs and forms a CsPbX
/Cs
GeF
hybrid structure. The theoretical calculations reveal that the CsPbBr
conversion proceeds at the Cs
GeF
edge through sequential growth of multiple PbBr
layers. Through the conversion strategy, luminescent and color-tunable CsPbX
QDs can be obtained, and these products present high stability against decomposition due to anchoring effects. Moreover, by partially converting red emissive Cs
GeF
:Mn
to green emissive CsPbBr
, the CsPbBr
/Cs
GeF
:Mn
hybrid can be employed as a low-lead hybrid perovskite phosphor on blue LED chips to produce white light. The leadless CsPbX
/Cs
GeF
hybrid structure with stable photoluminescence opens new paths for the rational design of efficient emission phosphors and may stimulate the design of other functional CsPbX
/Cs-containing hybrid structures.
In contrast with three-dimensional perovskites, their two-dimensional (2D) analogues have been demonstrated to effectively improve the moisture tolerance due to the hydrophobicity of the long-chain ...organic layers. However, the insulating property of the long-chain organic layers will deteriorate the charge transport properties of the materials, limiting their applications in photovoltaics and optoelectronics. Short-chain organic cation with less carbon atoms may be a good substitution for the preparation of 2D perovskites with superior environmental stability and optoelectronic properties. In this research, quasi-2D (C3H7NH3)2(MA)n-1PbnBr3n+1 perovskite nanocrystals with an average size smaller than 10 nm were synthesized by a one-pot method, showing tunable emissions in the range of 406–524 nm for n = 1∼∞, with corresponding band-gaps of 3.63–2.30 eV. Time-resolved photoluminescence (PL) decays show that (C3H7NH3)2PbBr4 has the shortest average PL lifetime of 4.4 ns with the fast decay process occupying weighting proportion of 87.3%. When the nominal perovskite layers increases up to 2–4, the average PL lifetime raises up to 10.1–41.7 ns, with the slow decay process taking up most weighting percentage of >70%. MAPbBr3 possesses the longest PL lifetime of 151.2 ns. The perovskite nanocrystals were then attempted to modify with oleic acid or to embed in PMMA matrix in order to improve their environmental stability. Results show that the stability of oleic acid and PMMA encapsulated nanocrystals improves greatly in comparison with bare nanocrystals.
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•Quasi-2D (C3H7NH3)2(MA)n-1PbnBr3n+1 perovskite nanocrystals.•Tunable emission ranging from 406 to 524 nm.•Enhanced stability.
2D halide perovskite materials have shown great advantages in terms of stability when applied in a photovoltaic device. However, the impediment of charge transport within the layered structure drags ...down the device performance. Here for the first time, a 3D–2D (MAPbI3‐PEA2Pb2I4) graded perovskite interface is demonstrated with synergistic advantages. In addition to the significantly improved ambient stability, this graded combination modifies the interface energy level in such a way that reduces interface charge recombination, leading to an ultrahigh Voc at 1.17 V, a record for NiO‐based p‐i‐n photovoltaic devices. Moreover, benefiting from the graded structure induced continuously upshifts energy level, the photovoltaic device attains a high Jsc of 21.80 mA cm−2 and a high fill factor of 0.78, resulting in an overall power conversion efficiency (PCE) of 19.89%. More importantly, it is showed that such a graded interface structure also suppresses ion migration in the device, accounting for its significantly enhanced thermal stability.
A designer cross‐dimensional perovskite–perovskite (3D–2D) interface upshifts the energy level toward the surface, pronouncedly reduces the charge recombination in perovskite photovoltaics, leading to a record high VOC at 1.17 V. Strongly enhanced ambient and thermal stability is also demonstrated.
Iodine‐based hybrid planar perovskite solar cells’ (PSCs) overall performance is still very limited. In this work, a highly functionalized iodine‐based hybrid perovskite layer is fabricated by ...incorporating trimethylolpropane ethoxylated triacrylate (TET) within the perovskite precursor, which can crosslink with the grain boundaries to improve the crystallinity as well as the grain size and passivate the defect states of the perovskite material. The MAPbI3‐based thin films with TET exhibited large grain sizes from 195.73 to 587.49 nm with 8 mg mL−1 of TET concentration. The X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X‐ray (EDX) elemental mapping, photoluminescence (PL), and time resolved photoluminescence (TRPL) characterization results suggest the strong crosslinking effect between TET and MAPbI3, which improves the crystallinity and reduces the charge trap density. Planar PSCs is fabricated with the device architecture fluorine‐doped tin oxide (FTO)/c‐TiO2/MAPbI3:TET/Spiro‐MeOTAD/Au and achieved a power conversion efficiency (PCE) of 14.75% under 1.5 AM light illumination. The fabricated PSCs shows excellent ambient stability which retains 80% of their PCE after being exposed to the ambient environment of relative humidity (RH) ≈60%, room temperature (RT) ≈27 °C without any encapsulation.
The incorporation of trimethylolpropane ethoxylated triacrylate (TET) as a crosslinker in MAPbI3 perovskite material improves crystalline quality, which results in an improvement in power conversion efficiency (PCE) from 10.95% to 14.75%. The films W‐TET and W/o‐TET exhibit grain sizes of 587.49 and 195.73 nm respectively. The larger the grain, the smaller the defect, which shows improved performance.
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•The CsPbBr3 PQDs composite was synthesized via a modified one-pot thermal polymerization strategy.•The CsPbBr3 PQDs composite with a record high PL-QY of 90% was obtained.•The ...CsPbBr3 PQDs composite shows an excellent long-term stability.•The embedded PQDs could be easily released from the copolymer matrix.•A white LED based on this composite exhibits a high luminous efficiency of 90 lm/W.
Practical application of colloidal fully inorganic perovskite-quantum-dots (PQDs) has been severely hindered because of their poor intrinsic stability and unsatisfactory photoluminescence quantum yields (PL QYs) in a powder state. Herein, we propose a new synthesis route to encapsulate CsPbBr3 PQDs with a poly-diphenylvinylphosphine-styrene copolymer (PDPEP-co-S) based on a one-pot hot-injection strategy. Different from conventional thermal polymerization, this strategy does not require any polar solvents during the synthesis process. The obtained CsPbBr3 PQDs@PDPEP-co-S composite powder possesses a record PL QY of 90%, which is the highest value ever reported for halide PQDs composites to date. More importantly, the encapsulated CsPbBr3 PQDs composite shows a good long-term stability against the external environment, such as water, methanol and UV light irradiation, which is of great significance for its practical application. Furthermore, the embedded CsPbBr3 PQDs are shown to be easily released from the copolymer matrix, which is very important for making all-solution-processed devices. Finally, a white light-emitting diode with a high luminous efficiency of 90 lm/W was successfully demonstrated based on these high-brightness CsPbBr3 PQDs@PDPEP-co-S phosphors, which indicates its promising potential in future illumination applications.
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•A facile in-situ emulsion method was used to construct Mn-DMSN support.•The support shows exceptionally ability to anchor Pt species by highly dispersed MnOx species.•The PtMn ...alloying extent obviously influence the activation of propane and desorption of propene.•Highly dispersed PtMn alloy nanoparticles play an important role in enhancing propane dehydrogenation performance.
The development of highly stable propane dehydrogenation catalyst is significant with the growing extraction of shale gas in the world. A highly dispersed MnOx site decorated dendritic mesoporous silica nanoparticle support was prepared by simple in-situ emulsion method. It shows exceptionally ability to disperse and stabilize Pt clusters. The strong interaction between Pt and Mn formed and the electron transfer happened from Mn to Pt, which leads to an increase in the electron density of Pt. The high propane dehydrogenation activity, even for 100 h long-term test, was obtained on moderate Mn content catalyst. According to the experimental results and DFT calculation, the highly dispersed PtMn alloyed nanoparticles play an important role in enhancing the catalytic performance for propane dehydrogenation via a good balance on propane activation and propene desorption.
Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a ...superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced stability and the stochastic resonant activation. (ii) Second, the electron spin relaxation process in a n-type GaAs bulk driven by a fluctuating electric field is investigated. In particular, by using a Monte Carlo approach, we study the influence of a random telegraph noise on the spin polarized transport. Our findings show the possibility to raise the spin relaxation length by increasing the amplitude of the external fluctuations. Moreover, we find that, crucially, depending on the value of the external field strength, the electron spin depolarization length versus the noise correlation time increases up to a plateau. (iii) Finally, the stabilization of quantum metastable states by dissipation is presented. Normally, quantum fluctuations enhance the escape from metastable states in the presence of dissipation. We show that dissipation can enhance the stability of a quantum metastable system, consisting of a particle moving in a strongly asymmetric double well potential, interacting with a thermal bath. We find that the escape time from the metastable region has a nonmonotonic behavior versus the system- bath coupling and the temperature, producing a stabilizing effect.
Organic/inorganic hybrid lead halide perovskites are promising optoelectronic materials due to their unique structure, excellent properties, and fascinating potential applications in lighting, ...photovoltaic, etc. However, perovskite materials are very sensitive to moisture and polar solvent, which greatly hinders their practical applications. Here, highly luminescent perovskite–polystyrene composite beads with uniform morphology are prepared via a simple swelling–shrinking strategy. This process is carried out only in nonpolar toluene and hexane without the addition of any polar reagents. As a result, the as‐prepared composite beads not only retain high luminescence but also exhibit superior water‐resistant property. The composites emit strong luminescence after being immersed into water over nine months. Moreover, even in some harsh environments such as acid/alkali aqueous solution, phosphate buffer solution, and Dulbecco's modified eagle medium biological buffers, they still preserve high luminescence. The applications in light‐emitting diodes and cellular labeling agents are also carried out to demonstrate their ultrastability.
Highly luminescent perovskite–polystyrene composite beads with uniform morphology are prepared by packing perovskite quantum dots in crosslinked polystyrene beads via swelling in toluene and then shrinking the beads in hexane. The composite not only retains high luminescence but also exhibits superior water resistance.
As a novel 2D material, black phosphorus (BP) nanosheets are considered as a promising candidate for drug delivery platform for synergistic chemo/photothermal therapy. However, the intrinsic ...instability of bare BP poses a challenge in its biomedical applications. To date, some strategies have been employed to prevent BP from rapid ambient degradation. Unfortunately, most of these strategies are not suitable for the drug delivery systems. Here, a simple polydopamine modification method is developed to enhance the stability and photothermal performance of bare BP nanosheets. Then, this nanocapsule is used as a multifunctional codelivery system for the targeted chemo, gene, and photothermal therapy against multidrug‐resistant cancer. The enhanced tumor therapy effect is demonstrated by both in vitro and in vivo studies.
A simple polydopamine modification method is developed to enhance the stability and photothermal performance of bare black phosphorus nanosheets. Then, this nanocapsule is used as a multifunctional codelivery system for the targeted chemo, gene, and photothermal therapy against multidrug‐resistant cancer. The enhanced tumor therapy effect is demonstrated by both in vitro and in vivo studies.
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