Ⅰ-Ⅲ-Ⅵ族半导体纳米晶:合成,性质及应用（英文）

半导体纳米晶具有独特的量子限域效应以及新颖的尺寸和形貌依赖特性,已被证实是在低成本高性能光伏器件、光致及电致发光二极管、生物成像、光催化等领域非常具有潜力的新型材料.其中,II-VI族与I-III-VI族半导体纳米晶由于其优异的性能在过去的数十年中引起了广泛的关注.过去数十年对于II-VI族半导体纳米晶的研究已经十分成熟,然而几乎所有的传统II-VI族半导体纳米晶都含有对环境有害的元素,对人体和环境造成不可逆转的伤害,从而限制了II-VI族半导体纳米晶的进一步应用.与二元II-VI族纳米晶相比,大部分三元I-III-VI族纳米晶不含镉和铅等重金属元素,因而具有低毒性的特点,并且其带隙窄、吸光收系数大、斯托克斯位移大、自吸收小以及发光波长在近红外区,所以有望使其成为新一代荧光纳米晶材料.例如,CuInS_2的带隙为1.53 eV,与太阳光谱匹配且其吸光系数较大,在10.5cm.~1左右,从而使其成为制备太阳能电池的一种优秀材料.另一方面,I-III-VI族纳米晶在可见光和近红外范围内呈现与尺寸相关的发光,它们的荧光量子产率在包覆ZnS壳后可超过50%,因而在照明,显示和生物成像领域具广泛应用的潜力.水溶性的I-III-VI族量子点粒径尺寸可以小于10 nm,可以减小纳米颗粒通过肾清除的淘汰率,并且具有高荧光性能和耐光性的特点,因此成为进行生物成像工作的优秀材料.与此同时,I-III-VI族纳米晶在光催化领域也展现了巨大的发展前景.本综述主要关注I-III-VI族纳米晶的合成,性质及应用.首先,我们概述了不同的化学合成方法,并列举讨论了一些经典的工作,根据纳米晶的种类分类统计了主要合成方法、形貌及尺寸.第二部分,我们讨论了它们的光物理和电子特性,解释了纳米晶的"donor-acceptor pair"(DAP)结合机理,概述了I-III-VI族纳米晶的磁光现象.接下来,我们概述了I-III-VI族纳米晶主要的应用领域,着重总结了在太阳能电池领域、半导体发光二极管领域、生物成像领域以及光催化制氢领域的研究进展.最后,我们会讨论半导体纳米晶的应用前景,以及它的机遇和挑战.

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.

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%.

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.

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.