Ligand modulation of active center to promote lead-free Cs_(2)AgInCl_(6)photocatalytic CO_(2)reduction

Metal halide perovskites(MHP)are potential candidates for the photocatalytic reduction of CO_(2)due to their long photogenerated carrier lifetime and charge diffusion length.However,the conventional long-chain ligand impedes the adsorption and activation of CO_(2)molecules in practical applications.Here,a ligand modulation technology is employed to enhance the photocatalytic CO_(2)reduction activity of lead-free Cs_(2)AgInCl_(6)microcrystals(MCs).The Cs_(2)AgInCl_(6)MCs passivated by Oleic acid(OLA)and Octanoic acid(OCA)are used for photocatalytic CO_(2)reduction.The results show that the surface defects and electronic properties of Cs_(2)AgInCl_(6)MCs can be adjusted through ligand modulation.Compared with the OLA-Cs_(2)AgInCl_(6),the OCA-Cs_(2)AgInCl_(6)catalyst demonstrated a significant improvement in the catalytic yield of CO and CH_(4).The CO and CH_(4)catalytic yields of OCA-Cs_(2)AgInCl_(6)reached 171.88 and34.15μmol g^(-1)h^(-1)which were 2.03 and 12.98 times higher than those of OLA-Cs_(2)AgInCl_(6),and the total electron consumption rate of OCA-Cs_(2)AgInCl_(6)was 615.2μmol g^(-1)h^(-1)which was 3.25 times higher than that of OLA-Cs_(2)AgInCl_(6).Furthermore,in situ diffuse reflectance infrared Fourier transform spectra revealed the enhancement of photocatalytic activity in Cs_(2)AgInCl_(6)MCs induced by ligand modulation.This study illustrates the potential of lead-free Cs_(2)AgInCl_(6)MCs for efficient photocatalytic CO_(2)reduction and provides a ligand modulation strategy for the active promotion of MHP photocatalysts.

Photo-and Electrocatalytic CO_(2)Reduction Based on Stable Lead-Free Perovskite Cs2PdBr6

All-inorganic lead-free palladium(Pd)halogen perovskites with prominent optoelectronic properties provide admirable potential for selective photo-and electroreduction of CO_(2).But it remains unachieved for effectively converting the CO_(2)to CO with high selectivity on Pd-based perovskites driven by solar light or electricity.Herein,high-quality Cs_(2)PdBr_(6)microcrystals and nanocrystals were synthesized through a facile antisolvent method.Among all the reported pure-phase perovskites,the Cs_(2)PdBr_(6)nanocrystals synthesized at 50℃performed the highest effectiveness on CO_(2)to CO conversion generating 73.8μmol g^(-1)of CO yield with 100%selectivity under visible light illumination(λ>420 nm)for 3 h.Meanwhile,for the first time,we report a new application of lead-free perovskites,in which they are applied to electrocatalysis of CO_(2)reduction reaction.Noticeably,they showed significant electrocatalytic activity(Faradaic yield:78%for CO)and operation stability(10 h).And the surface reaction intermediates were dynamically monitored and precisely unraveled according to the in situ diffuse reflectance infrared Fourier transform spectra investigation.In combination with the density functional theory calculation,the reaction mechanism and pathways were revealed.This work not only provides significant strategies to enhance the photocatalytic performance of perovskites,but also shows excellent potential for their application in electrocatalysis.

Ⅰ-Ⅲ-Ⅵ chalcogenide semiconductor nanocrystals:Synthesis,properties,and applications

Colloidal semiconductor nanocrystals have been proven to be promising candidates for applications in low‐cost and high‐performance photovoltaics,bioimaging,and photocatalysis due to their novel size‐and shape‐dependent properties.Among the colloidal systems,I‐III‐VI semiconductor nanocrystals(NCs)have drawn much attention in the past few decades.Compared to binary NCs,ternary I‐III‐VI NCs not only exhibit low toxicity,but also a high performance similar to that of binary NCs.In this review,we mainly focus on the synthesis,properties,and applications of I‐III‐VI NCs.We summarize the major synthesis methods,analyze their photophysical and electronic properties,and highlight some of the latest applications of I‐III‐VI NCs in solar cells,light‐emitting diodes,bioimaging,and photocatalysis.Finally,based on the information reviewed,we highlight the existing problems and challenges.

相位分布管理的准二维钙钛矿薄膜在纳秒脉冲激光泵浦下实现高效放大自发发射

准二维钙钛矿表现出独特的光物理性质,这使它们成为激光技术潜在进步的优秀候选材料.高性能纳秒脉冲激光和放大自发发射(ASE)是实现连续波抽运光电泵浦激光器的关键工艺.然而,在纳秒脉冲激光泵浦下发展准二维钙钛矿ASE或激光仍然存在一些困难,包括表面缺陷浓度高、俄歇复合和能量传递效率低.本文通过无添加剂的Cs^(+)阳离子掺杂策略,可以很好地控制准二维钙钛矿膜的形貌和相分布,从而解决了低n相导致的能量传递途径不足的问题.本文通过快速的能量传递过程揭示了增益性质和载流子复合.基于此,掺杂适当比例Cs^(+)阳离子的PEA_(2)(FA_(0.7)Cs_(0.3))_(2)Pb_(3)Br_(10)钙钛矿膜的净增益系数比原始钙钛矿薄膜提高了近3倍,从而将纳秒激光激发下的放大自发发射阈值降低到1/3.研究结果表明,在准二维钙钛矿中掺杂Cs^(+)可为实现高性能激光器件的相位分布设计提供见解.

Organic-2D composite material-based RRAM with high reliability for mimicking synaptic behavior

The field of artificial intelligence and neural computing has been rapidly expanding due to the imple-mentation of resistive random-access memory(RRAM)based artificial synaptic.However,the low flexibility of conventional RRAM materials hinders their ability to mimic synaptic behavior accurately.To overcome such limitation,organic-2D composites with high mechanical properties are proposed as the active layer of RRAM.Moreover,we enhance the reliability of the device by ZrO_(2)insertion layer,resulting in stable synaptic performance.The Ag/PVA:h-BN/ZrO_(2)/ITO devices show stable bipolar resistive switching behavior with an ON/OFF ratio of over 5×10^(2),a~2400 cycles endurance and a long retention time(>6×10^(3)s),which are essential for the development of high-performance RRAMs.We also study the possible synaptic mechanism and dynamic plasticity of the memory device,observing the transition from short-term potentiation(STP)to long-term potentiation(LTP)under the effect of continuous voltage pulses.Moreover,the device exhibits both long-term depression(LTD)and paired-pulse facili-tation(PPF)properties,which have significant implications for the design of organic-2D composite material RRAMs that aim to mimic biological synapses,representing promising avenues for the devel-opment of advanced neuromorphic computing systems.

Advances in metal halide perovskite lasers: synthetic strategies, morphology control, and lasing emission

.In the past decade,lead halide perovskites have emerged as potential optoelectronic materials in the fields of light-emitting diode,solar cell,photodetector,and laser,due to their low-cost synthesis method,tunable bandgap,high quantum yield,large absorption,gain coefficient,and low trap-state densities.In this review,we present a comprehensive discussion of lead halide perovskite applications,with an emphasis on recent advances in synthetic strategies,morphology control,and lasing performance.In particular,the synthetic strategies of solution and vapor progress and the morphology control of perovskite nanocrystals are reviewed.Furthermore,we systematically discuss the latest development of perovskite laser with various fundamental performances,which are highly dependent on the dimension and size of nanocrystals.Finally,considering current challenges and perspectives on the development of lead halide perovskite nanocrystals,we provide an outlook on achieving high-quality lead perovskite lasers and expanding their practical applications.

Tunable luminescent CsPb_2Br_5 nanoplatelets:applications in light-emitting diodes and photodetectors

Unlike organic–inorganic hybrid perovskites, all-inorganic cesium lead halide perovskites hold great promise for developing high-performance optoelectronic devices, owing to their improved stability. Herein, we investigate the perovskite-related CsPb_2 Br_5 nanoplatelets(NPLs) with tunable emission wavelengths via changing the reaction temperatures to 100°C, 120°C, and 140°C. Reaction temperature plays a key role in determining the shapes and thicknesses of the resulting CsPb_2 Br_5 NPLs. A higher temperature is in favor of the formation of smaller and thicker NPLs. To develop their potential applications in optoelectronic devices, green light emitting diodes(LEDs) and photodetectors based on CsPb_2 Br_5 NPLs are fabricated. The green LEDs based on CsPb_2 Br_5 NPLs synthesized at 140°C exhibit an excellent pure green emission(full width at half-maximum of <20 nm) and display a luminous efficiency of 34.49 lm∕W under an operation current of 10 m A. Moreover, the photodetector based on CsPb_2 Br_5 NPLs synthesized at 100°C has better performance with a rise time of 0.426 s, a decay time of0.422 s, and a ratio of the current(with and without irradiation) of 364%.

Mode selection and high-quality upconversion lasing from perovskite CsPb2Br5 microplates

In recent years,halide perovskite nanostructures have had great advances and have opened up a bright future for micro/nanolasers.However,upconversion lasing by two-photon excitation with mode selection and high quality factor in one device is still rarely reported.Herein,two lasing modes are demonstrated in the all-inorganic perovskite CsPb2Br5 microplates with subwavelength thickness and uniform square shape.The net optical gain is quickly established in less than 1 ps and persists more than 30 ps,revealed by ultrafast transient absorption spectroscopy.The temperature-dependent low-threshold amplified spontaneous emission confirms the net gain for stimulated emission with a high characteristic temperature of 403 K,far surpassing the all-inorganic CsPbBr3 semiconductor gain media.Remarkably,upconversion lasing based on two kinds of microcavity effects,Fabry–Pérot and whispering-gallery modes,from the microplates at room temperature is successfully achieved with a low threshold operating in multi-or single-mode,respectively.Surprisingly,the quality factor(~3551)is among the best values obtained from perovskite micro/nanoplate upconversion lasers without an external cavity.Moreover,the highly stable chromaticity with color drift only less than 0.1 nm also outbalances the all-inorganic CsPbBr3 ones.These superior performances of CsPb2Br5 microplate lasing with a facile solution synthesis procedure will offer a feasible structure to fabricate specific functionalities for high-performance frequency upconversion micro/nanoscale photonic integrated devices.

Surface ligand modified cesium lead bromide/silica sphere composites for low-threshold upconversion lasing

In recent years,all-inorganic halide perovskite quantum dots(QDs)have drawn attention as promising candidates for photodetectors,light-emitting diodes,and lasing applications.However,the sensitivity and instability of perovskite to moisture and heat seriously restrict their practical application to optoelectronic devices.Recently,a facile ligand-engineering strategy to suppress aggregation by replacing traditional long ligands oleylamine(OAm)during the hot injection process has been reported.Here,we further explore its thermal stability and the evolution of photoluminescence quantum yield(PLQY)under ambient environment.The modified CsPbBr_(3)QDs film can maintain 33%of initial PL intensity,but only 17%is retained in the case of unmodified QDs after 10 h continuous heating.Further,the obtained QDs with higher initial PLQY(91.8%)can maintain PLQY to 39.9%after being continuously exposed in air for 100 days,while the PLQY of original QDs is reduced to 5.5%.Furthermore,after adhering CsPbBr3 QDs on the surface of a micro SiO_(2)sphere,we successfully achieve the highly-efficient upconversion random laser.In comparison with the unmodified CsPbBr_(3)QDs,the laser from the modified CsPbBr_(3)QDs presents a decreased threshold of 79.81μJ/cm^(2)and higher quality factor(Q)of 1312.This work may not only provide a facile strategy to synthesize CsPbBr_(3) QDs with excellent photochemical properties but also a bright prospect for high-performance random lasers.

Facile synthesis of Cu-In-Zn-S alloy nanospheres for fast photoelectric detection across the visible spectrum

Fast and broadband photoelectric detection is a key process to many photoelectronic applications,during which the semiconductor light absorber plays a critical role.In this report,we prepared Cu-In-Zn-S(CIZS)nanospheres with different compositions via a facile hydrothermal method.These nanospheres were^200 nm in size and comprised of many small nanocrystals.A photodetector responded to the visible spectrum was demonstrated by spraying the solution processed nanospheres onto gold interdigital electrodes.The photoelectric characterization of these devices revealed that CIZS nanospheres with low molar ratio of n(Cu)/n(In)exhibited improved photoelectric response compared to those with high n(Cu)/n(In),which was attributed to the reduced defects.The relatively large switching ratio(Ion/Ioff),fast response and wide spectral coverage of the CIZS-based photodetector render it a promising potential candidate for photoelectronic applications.