Abstract ：

Phase control of random lasing processes has been a challenge both in physics and in the device/materials design. Although conventional saturable absorbers can be integrated with random lasers to conceive mode-locking scheme, low intensity and random directions of the lasing radiation reduce largely the possibility. In such considerations, we put forth a new mode-locking mechanism, which is defined as cascaded absorption and stimulated emission (CASE), and have it achieved in multicrystalline microdisk structures of a hybrid perovskite. This scheme applies only to lasing materials with strong overlap between the absorption and emission spectra. In this work, we employed 2-photon pumping at 800 nm with a pulse duration of about 150 fs to realize phase-locked random lasing in MAPbBr3 microdisks in donut shapes, which are produced by micro-imprinting using a flexibly transferred template of tricyclo[5.2.1.02,6] decanedimethanol diacrylate. The phase-locking performance is identified by the narrow-band lasing lines with equal separations. The constant phase shift for initializing phase locking is determined by the internal conversion lifetime in the MAPbBr3 molecules. Two-photon pumping enables large penetration depth into the microdisks and consequently large numbers of phase-locked lasing modes, producing much narrowed and high-contrasted spectral lines. Lasing lines with a bandwidth as narrow as 0.26 to 0.3 nm and an equal separation ranging from 1.7 to 4.8 nm have been achieved for different microdisk schemes. These results imply marked progress in new random lasing physics and potential applications in ultrafast laser technology. © 2024 Qin Zhang et al.

Keyword ：

Two photon processes Mode-locked fiber lasers Granite Metamorphic rocks Ultrafast lasers Atomic emission spectroscopy Photons Optical pumping Saturable absorbers

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Violet-emitting perovskite quantum dots (QDs) are of great significance for theoretical and experimental research aimed at promoting the development of environmentally friendly violet light-emitting diodes (LEDs). Nevertheless, the synthesis of violet perovskite QDs via ligand-assisted reprecipitation is challenging due to the significant bandgap. A simple and economical cryo-bonding ligand-assisted reprecipitation (Cb-LARP) method is proposed as a means of synthesizing deep violet lead-free organic-inorganic hybrid perovskite (OIHP) QDs, with the objective of increasing the bandgap in the material. The MA(3)Bi(2)Br(9) QDs synthesized by the Cb-LARP method exhibit bright violet luminescence at 400 nm, with a PLQY of 50.1%. Moreover, the photoluminescence peak of the QDs can be adjusted from 402 to 393 nm by modifying the final reaction time. It is noteworthy that the MA(3)Bi(2)Br(6)Cl(3) QDs exhibited ultraviolet emission at 379 nm, corresponding to a PLQY of 35.4%. Similarly, the emission peak of the QDs can be tuned from 379 to 376 nm by changing the final reaction time. The results demonstrate that the deep violet emitting OIHP QDs have been successfully synthesized. This study provides a theoretical reference for short-wavelength perovskite materials and an experimental reference for the study of violet and UV quantum-dot light-emitting diode devices.

Keyword ：

ultraviolet light Cb-LARP perovskite structure quantum dots

Cite：

Copy from the list or Export to your reference management。

Abstract ：

We report a Mn2+-activated all-inorganic 2D layered Ruddlesden-Popper (RP) perovskite Cs2CdCl4 single crystal as a highly efficient and stable X-ray scintillator. The Cs2CdCl4:10% Mn achieves a bright orange-red emission with a photoluminescence quantum yield up to 90.47%, good environmental stability, and decent thermal quenching resistance. As a scintillator, Cs2CdCl4:10% Mn shows strong X-ray absorption, ultrahigh light yield up to 88138 photons/MeV, and low detection limit of 31.04 nGy(air)/s. A 15 x 15 cm flexible scintillation screen is prepared by mixing poly(dimethylsiloxane) (PDMS) with Cs2CdCl4:Mn powder, which demonstrates superior X-ray imaging performance with a high spatial resolution of 16.1 lp mm(-1) at a modulation transfer function (MTF) = 0.2. Importantly, due to the ultrahigh X-ray sensitivity, the flexible scintillator screen achieved clear X-ray imaging at an extremely low dose of 16 mu Gy(air)/s. This successful exploitation of the 2D high light yield perovskite scintillator in flexible low-dose X-ray imaging would provide new insight into high-sensitivity X-ray detection.

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Metal halide perovskites are considered as a prospective candidate as optical gain media for stimulated emission, and the advancement of amplified spontaneous emission (ASE) of perovskite materials is gradually becoming the key to realize the commercialization of perovskite lasers. Nonetheless, the ASE of solution-processed polycrystalline perovskite films still experiences a high threshold and poor optical stability due to their high defect density and poor crystalline quality. In this scenario, a noticeably ameliorated ASE performance with decreased threshold and greater photo-stability is demonstrated in solution-processed (FAPbI(3))(0.85)(MAPbBr(3))(0.15) polycrystalline perovskite films by introducing a neoteric 4 '-Aminoacetophenone hydrochloride (APCl) additive with cost-effective fabrication. The ASE threshold of the APCl-embedded perovskite films is prominently curtailed from 12.8 to 5.3 mu J cm(-2), with an augmented optical gain, ASE output intensity, and optical durability. The ameliorated ASE performance can be credited to multifunctional effects of the APCl additive in the perovskite films, presenting a low defect density, an unambiguously elevated photoluminescence, a prolonged decay lifetime and thus enabling the easily achieved population inversion caused by the attenuated nonradiative carrier recombination in the optical gain media. These findings provide a significant foundation and pave the way for realizing the electrically excited lasing based on the perovskite materials.

Keyword ：

optical durability 4 '-Aminoacetophenone hydrochloride perovskite films threshold amplified spontaneous emission

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Inverted p-i-n structure perovskite solar cells (PSCs) have attracted considerable attention in consideration of high-efficiency, long-term stability, and cost reduction, which represent the key challenges in advancing the commercialization of PSCs. In order to address the issue of defect-related nonradiative recombination, we enhanced the interfacial passivation between the perovskite layer and electron transfer layer with crown ether derivatives in p-i-n PSCs. By a combination of first-principles calculations, photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra, and grazing-incidence wide-angle X-ray scattering (GIWAXS) characterization, we provided an understanding of the passivation mechanism and obtained an efficiency of 23.3% in NiOx-based p-i-n PSCs, which lowered the nonradiative recombination with 25% of the voltage losses. Furthermore, the unencapsulated PSCs kept 92% of the initial efficiency following 1224 h of aging, which demonstrated remarkable long-term stability. The inverted structure with interfacial passivation could provide great potential for high-efficiency and stable PSC designs and promote the commercialization of PSCs.

Cite：

Copy from the list or Export to your reference management。

Abstract ：

The promising prospects of antiferroelectric perovskite oxides in the realm of energy storage applications hinge on the unique field-induced phase transitions. Once the transition is triggered by the application of an electric field, characteristic double polarization loops appear. However, NaNbO3-based 3-based materials that exhibit a reversible phase transition are still rare, which hinders the practical applications of lead-free antiferroelectrics. Here, the impact of materials chemistry on the competition between antiferroelectric and ferroelectric states is demonstrated in a series of NaNbO3-based 3-based solid solutions with varying perovskite B-site cations, while the A-site is fixed as strontium. The crystal structure is analyzed on the basis of Rietveld refinement of high-energy X-ray diffraction data. The phase transition behavior as well as the antiferroelectric and ferroelectric properties are probed by a series of electrical measurements. The antiferroelectric phase is universally observed for all investigated materials in the virgin state. The SrTiO3-substituted 3-substituted system shows an irreversible phase transition similar to that of pure NaNbO3. In contrast, double polarization hysteresis loops are observed in the SrHfO3-, SrZrO3-, and SrSnO3-substituted 3-substituted systems. It is confirmed that compounds that can reduce the tolerance factor of the system contribute to the stabilization of the antiferroelectric order, while those that can reduce the electronegativity difference lead to more pronounced double loops. The competition between antiferroelectricity and ferroelectricity is linked to the competition between covalent and ionic bonding in perovskites.

Keyword ：

Sodium niobate Phase transition Lead free Electrical properties Antiferroelectric

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Perovskite solar cells have made significant strides in recent years. However, there are still challenges in terms of photoelectric conversion efficiency and long-term stability associated with perovskite solar cells. The presence of defects in perovskite materials is one of the important influencing factors leading to subpar film quality. Adopting additives to passivate defects within perovskite materials is an effective approach. Therefore, we first discuss the types of defects that occur in perovskite materials and the mechanisms of their effect on performance. Then, several types of additives used in perovskite solar cells are discussed, including ionic compounds, organic molecules, polymers, etc. This review provides guidance for the future development of more sustainable and effective additives to improve the performance of solar cells.

Keyword ：

defect passivation perovskite solar cells ionic compounds organic molecules

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Zero-dimensional (0D) hybrid manganese halides have gained wide attention for the various crystal structures, excellent optical performance and scintillation properties compared with 3D lead halide perovskite nanocrystals. In this work, a new family of 0D hybrid manganese halides of A2MnBr4 (A = BzTPP, Br-BzTPP, and F-BzTPP) based on discrete [MnBr4]2− tetrahedral units is reported as highly efficient lead-free scintillators. Excited by UV or blue light, these hybrids emit bright green light originating from the d–d transition of Mn2+ with near-unity PLQY (99.5%). Significantly, high PLQY and low self-absorption render extraordinary radioluminescence properties with the highest light yield of 80,100 photons MeV−1, which reached the climax of present hybrid manganese halides and surpassed most commercial scintillators. The radioluminescence intensity features a linear response to X-ray doses with a detection limit of 30 nGyair s−1, far lower than the requirement of medical diagnostic (5.5 µGyair s−1). X-ray imaging demonstrates ultrahigh spatial resolution of 14.06 lp mm−1 and short afterglow of 0.3 ms showcasing promising application prospects in radiography. Overall, we demonstrated new hybrid manganese halides as promising scintillators for advanced applications in X-ray imaging with multiple superiorities of nontoxicity, facile-assembly process, high irradiation light yield, excellent resolution, and stability. © 2024 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.

Keyword ：

Phosphors Lead compounds Scintillation counters Diagnosis Manganese compounds Ionization Perovskite Medical imaging Bromine compounds

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Understanding the function of individual elements in high -entropy perovskites is one of the critical issues for the design of inexpensive and efficient bifunctional electrocatalysts. Here, we report our findings in boosting the electrochemical activity and durability of a high -entropy perovskite catalyst via sequential substitution of Sr2+ for the A -site elements. According to the Sr2+ localized tuned, the catalyst of (LaSmGdSrPr)0.2MnO3 has a halfwave potential of 0.786 V vs. RHE and an overpotential of 0.378 V and has better ORR and OER electrocatalytic activity than the Sr -free high -entropy perovskite catalyst (LaSmGdYPr)0.2MnO3.This is attributed to the local doping of Sr2+ activating the active center of the high -entropy perovskite catalyst (LaSmGdSrPr)0.2MnO3, modulating the adsorption energy of the oxygen -containing intermediates and the electronic structure of the transition metal at the B -site, which results in efficient oxygen electrocatalytic activity. On the other hand, the introduction of Sr2+ enhances the hybridization between Mn 2p and O 1 s and accelerates the adsorption and desorption kinetics of the intermediates, leading to both enhanced activity and durability of (LaSmGdSrPr)0.2MnO3. DFT theoretical calculations also demonstrate the key role played by Sr2+ in the highentropy perovskite structure for the improvement of the electrocatalytic activity. This study provides new insights for designing high -entropy electrocatalysts for various potential applications.

Keyword ：

Electronic structure High -entropy perovskite DFT calculation Catalytic performance

Cite：

Copy from the list or Export to your reference management。

Abstract ：

Compositional heterogeneity is commonly observed in mixed bromide/iodide perovskite photoabsorbers, typically with minimal effects on charge carrier recombination and photovoltaic performance. Consistently, it has so far received very limited attention in bromide/chloride-mixed perovskites, which hold particular significance for blue light -emitting diodes. Here, we uncover that even a minor degree of localized halide heterogeneity leads to severe non -radiative losses in mixed bromide/chloride blue perovskite emitters, presenting a stark contrast to general observations in photovoltaics. We not only provide a visualization of the heterogeneity landscape spanning from micro -to sub-microscale but also identify that this issue mainly arises from the initially formed chloride -rich clusters during perovskite nucleation. Our work sheds light on a long-term neglected factor impeding the advancement of blue light -emitting diodes using mixed halide perovskites and provides a practical strategy to mitigate this issue.

Cite：

Copy from the list or Export to your reference management。