Transition metal chalcogenides (TMCs) have wide-ranging applications in nanoelectronics and optoelectronics due to their unique energy band structure and excellent properties. Iron(Ⅱ) sulfide quantum dots (FeS QDs) are environmentally friendly semiconductor material and exhibit excellent near-infrared properties because of their narrow bandgap, which is essential for infrared detectors. In this paper, FeS QDs were prepared by liquid phase ultrasonic exfoliation and the solution of FeS QDs was spin-coated on a quartz substrate to form a film. The morphology, structural and optical properties of FeS QDs solutions and films were studied. FeS QDs demonstrated good dispersion with average particle size and height of approximately 11.7 and 10.4 nm, respectively. The calculated average particle size of FeS QDs was 12.7 nm using the Debye-Scherrer formula, which is in good agreement with the TEM characterization. The ultraviolet-visible-near infrared (UV-Vis-NIR) characterization of the FeS QDs solutions and films exhibited obvious absorption in the ultraviolet to near-infrared wavelength band, and the absorption was stable in the near-infrared wavelength band. The photoluminescence (PL) characterization of the FeS QDs solutions and films revealed luminescence properties in the near-infrared wavelength band, and the peak position appeared to be red-shifted with an increase in excitation wavelength, which suggests excitation wavelength-dependent luminescence properties. The FeS QDs exhibit good infrared characteristics and can potentially be used in infrared photovoltaic and photodetector.

Cobalt sulfide (CoS) is a zero bandgap transition metal chalcogenides (TMCs). However, the bandgap of CoS can be altered when it exists as low-dimensional material, such as quantum dots (QDs), via different preparation methods. In this work, CoS QDs were successfully prepared by liquid-phase ultrasonic exfoliation method and CoS QDs film was obtained by spin coating CoS QDs solution onto a substrate. The morphology, structural, chemical properties, thickness, vibration peaks and chemical bonds of CoS QDs were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), atomic force microscopy (AFM), Raman spectroscopy (Raman) and X-ray photoelectron spectroscopy (XPS). The absorption and fluorescence characteristics of the CoS QDs were studied using ultraviolet-visible-near infrared (UV-Vis-NIR) and fluorescence spectroscopies. Results show that the average size of CoS QDs was 9.1 nm and average thickness was 8.4 nm and CoS QDs solution and film exhibited absorption in the infrared band. With an increase of excitation and emission wavelength, both the photoluminescence (PL) peak and photoluminescence excitation (PLE) peak of CoS QDs solution and film showed red-shift, which demonstrates Stokes shift effect and dependency on wavelength and have near-infrared luminescence characteristics. The infrared absorption and near-infrared luminescence properties of CoS QDs solution and film imply that they can be found important application in the field of infrared detection. Such novel material is expected to play a crucial role in low-cost, high performance infrared photodetector.

采用液相超声剥离法成功制备了CoS量子点(QDs),使用透射电子显微镜(TEM)对CoS QDs的形貌和结构进行了表征,利用紫外—可见分光光度计(UV-Vis)和荧光光谱仪(PL)测试了样品的吸光度和不同激发波长下的荧光强度.测试结果表明:在离心转速为4500、3000 r/min和1 500 r/min时,CoS QDs的平均尺寸分别为3.4、3.6 nm和4.4 nm;三种尺寸的CoS QDs具有宽带光吸收特性,并且随着量子点尺寸的增加,CoS QDs的吸收范围逐渐变宽,PL峰表现出Stokes位移和激发波长依赖性.

Objective Compared with other quantum dots(QDs),infrared QDs have narrower band gaps,wider absorption ranges,and longer fluorescence wavelengths.Therefore,they show greater potential in areas such as bioimaging,tumor treatment,photodetector and solar concentrators.As transition metal chalcogenides(TMCs),FeS QDs are promising infrared detection materials due to their narrow band gap,low toxicity,and strong near-infrared absorption.Forming therm into thin films is an effective approach to enhance the stability and processability of QDs.At present,the research about FeS mainly focuses on nanofilms and nanoparticles,and there are few reports on FeS QDs and their composite films.In this paper,we studied the preparation of FeS QDs by liquid-phase ultrasonic exfoliation,and prepared FeS/PVA composite films by mixing FeS QDs with polyvinyl alcohol(PVA).We tested and analyzed the infrared characteristics of FeS QDs in order to explore their potential applications in the field of infrared,and its application in the field of infrared optics was prospected. Methods FeS QDs solution was prepared by liquid phase ultrasonic exfoliation method.The preparation steps were as follows:0.15 g of FeS powder(purity ≥99.9％)was weighed and placed in a mortar,followed grinding for 2 h.The ground FeS powder was then mixed with 50 mL of isopropyl alcohol(IPA,purity ≥99.7％)dispersant,and placed in the ultrasonic instrument at 120 W power for 2 h.After ultrasonic,the solution was centrifuged at 500 r/min for 5 minutes,taking out the supernatant,FeS QDs solution was obtained.Collect in a reagent bottle for further use. FeS QDs/PVA nanocomposite films were prepared using a blending method,following the steps below:0.4 g of PVA powder was weighed and added to a beaker containing 20 mL of deionized water.The mixture was placed on a magnetic heating stirrer and continuously stirred at elevated temperature for 45 min until the powder was completely dissolved.Then,4 mL of the FeS QDs solution was added to the mixture,and the heating and stirring kept on an additional 15 min.Subsequently,4 mL of the mixed solution was drop-cast onto a metal sample holder,and the film was formed by heating the sample holder on a heating plate at 40 ℃ for 4 h. FeS QDs were characterized and analyze for size,morphology,structure,and elemental composition using transmission electron microscopy(TEM),atomic force microscopy(AFM),and energy spectroscopy(EDS).The phase composition and bonding properties of FeS QDs were analyzed by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and Raman spectroscopy.The optical properties of FeS QDs and FeS QDs/PVA nanocomposite films were studied using UV-Vis spectrophotometer and fluorescence spectrometer. Results and Discussions Both FeS QDs and FeS QDs/PVA nanocomposite films exhibit significant absorption and luminescence characteristics in the infrared band(Fig.4(a),(b),(c)).As the excitation wavelength increase,the PL peak of the FeS QDs/PVA nanocomposite film shows a clear redshift,which shows obvious Stokes shift and excitation wavelength dependence(Fig.5(e)). Conclusions FeS QDs with an average particle size of 8.1 nm were successfully prepared by liquid phase ultrasonic exfoliation method.FeS/PVA nanocomposite films were prepared by blending FeS QDs with PVA.UV-Vis tests show that FeS QDs and FeS/PVA nanocomposite films exhibit absorption from ultraviolet to infrared band(200-2500 nm).PL test shows that they have photoluminescence in infrared band.PL peaks show significant redshift and Stokes shift,indicating that both are wavelength dependence.In addition,FeS/PVA nanocomposite film shows excellent infrared optical properties,especially the absorption and luminescence characteristics in the infrared band.These results show that FeS QDs and its nanocomposite films have important application potential in the field of infrared optics,and provide a new idea for the development of infrared optical devices.

采用液相超声剥离法制备了尺寸可控的FeS量子点(QDs),通过改变离心转速得到不同粒径的FeS QDs.利用TEM对FeS QDs的形貌和结构进行了表征;通过UV-Vis和PL光谱研究了FeS QDs的光学特性.结果表明:当离心转速分别为4 500、3 000 r/min和1500 r/min时,对应的FeS QDs平均尺寸为2.6、3.0 nm和3.5 nm;三组样品在紫外到红外波段(200～2 000 nm)均有吸收,随着波长的增加吸收强度缓慢下降;此外,研究发现FeS QDs具有光致发光特性,随着激发光波长增加PL峰红移,表明其发光具有波长依赖性.

Herein, SnSe2 QDs have successfully been prepared by liquid-phase ultrasonic exfoliation of the group IV metal-sulfide compounds. The morphology and structure of the SnSe2 QDs were characterized by transmission electron microscopy (TEM) and high-resolution transmission microscopy (HR-TEM), and the composition of the materials was analyzed by X-ray diffraction (XRD) and Raman spectroscopy (Raman). The absorbance of the samples with different wavelengths was analyzed by UV-Vis spectrophotometer, and the fluorescence intensity at different excitation wavelengths was studied by fluorescence spectrometer (PL), and the effect of different centrifugal speeds on the particle size of QDs and the spectral red-shift caused by the size effect was investigated. The average lateral sizes of SnSe2 QDs samples obtained at centrifugal speeds of 3500, 1500 and 500 rpm were 1.86 nm, 2.73 nm, and 3.3 nm, respectively. The SnSe2 QDs exhibited significant absorption in the infrared band and red-shift with increasing QDs size, The results demonstrated the potential use of this new material in infrared detection.

量子点因具有优异的光电特性，近年来备受关注。但量子点的规模化应用因受到其加工工艺及稳定性等因素限制而尚待开发。量子点-聚合物纳米复合材料的出现有效弥补了这一问题，将量子点分散到有机聚合物中形成纳米复合材料，集合量子点与聚合物的各自优势于一体，是解决量子点当前应用问题的一种有效方法，具有显著的发展潜力。文中介绍了量子点的主要制备技术，并在此基础上对量子点-聚合物复合材料的制备方法及其在激光器、发光二极管、光电探测器、量子点电视等光电子器件中的应用进展进行了概述，最后对其在光电器件领域的应用进行了展望。

以石墨和纯的TiO2为原料,采用球磨工艺制备了石墨/TiO2复合光催化剂.使用XRD、SEM、TEM、XPS和DRS等手段对其性能进行了表征.以甲基橙为模拟污染物,研究了石墨掺入量、球磨时间对复合光催化剂光催化活性的影响.结果 表明,石墨/TiO2复合光催化剂具有锐钛矿结构,球磨后TiO1(101)面的衍射峰宽化并右移,TiO2成为200 nm左右的不规则球状颗粒,在其表面均匀分布着石墨.TiO2晶粒的Ti-O键的结合能变高,且表面有缺陷产生,使其在可见光区具有显著的吸收.石墨掺入量为5％、球磨时间为12h的石墨/TiO2样品对甲基橙具有优异的光催化降解效果,在70 min的降解时间内甲基橙的降解去除率可达95.08％.石墨/TiO2复合光催化剂的光催化反应速率常数k为0.043035 min-1,是纯TiO2的2.64倍.

近年来,过渡金属碲化物(TMTs)以其独特的晶体结构和优异的物化特性引起了科学界的广泛关注和研究.本文采用超声法制备CoTe2量子点(QDs),通过TEM、AFM、EDS、XPS、XRD、FTIR等技术手段对制备的CoTe2 QDs进行了形貌和结构的表征,同时使用分光光度计(UV-Vis)、光致发光谱(PL)和光致发光激发光谱(PLE)研究了CoTe2 QDs的光学性质.结果表明,制备得到的CoTe2 QDs分散性良好、粒径均匀、呈现球形形貌,晶粒的平均直径约为3.1 nm,平均高度约为2.9 nm;CoTe2 QDs在红外波段存在明显的吸收,吸收值随稀释浓度的增加而降低;当激发光波长和发射光波长依次增加时,PL和PLE峰出现红移,具有明显的Stokes位移效应,表明CoTe2 QDs的光致发光具有激发波长依赖性;CoTe2 QDs具有光致多色发光特性,不同激发光波长可发出不同颜色的光;荧光量子产率可达62.6％.CoTe2 QDs优异的光学特性尤其是在红外波段的吸收和发光特性,表明其在红外探测、激光防护涂层、荧光成像、多色发光和纳米光子器件等研究领域中具有重要的潜在应用价值,有望成为一种新型红外探测材料.

Tantalum disulfide (TaS2) two-dimensional film material has attracted wide attention due to its unique optical and electrical properties. In this work, we report the preparation of 1 T-TaS2 quantum dots (1 T-TaS2 QDs) by top-down method. Herein, we prepared the TaS2 QDs having a monodisperse grain size of around 3 nm by an effective ultrasonic liquid phase exfoliation method. Optical studies using UV-Vis, PL, and PLE techniques on the as-prepared TaS2 QDs exhibited ultraviolet absorption at 283 nm. Furthermore, we found that dimension reduction of TaS2 has led to a modification of the band gap, namely a transition from indirect to direct band gap, which is explained using first-principle calculations. By using quinine as reference, the fluorescence quantum yield is 45.6%. Therefore, our results suggest TaS2 QDs have unique and extraordinary optical properties. Moreover, the low-cost, facile method of producing high quality TaS2 QDs in this work is ideal for mass production to ensure commercial viability of devices based on this material. TaS2 quantum dots having a monodisperse grain size of around 3 nm have been prepared by an ultrasonic liquid phase exfoliation method, it has been found that the dimension reduction of TaS2 has led to a transition from indirect to direct band gap that results in the unique and extraordinary optical properties (PL QY: 45.6%).

碲化锑(Sb2Te3)是一种新型二维层状材料,采用"自上而下"的超声剥离法,以碲化锑粉末为原料,以N-甲基吡咯烷酮(NMP)为分散剂,首次成功制备出碲化锑量子点(Sb2Te3 QDs),并采用多种手段(SEM,TEM,AFM,XPS,XRD等)对所制备Sb2Te3 QDs的形貌和结构进行了表征,同时还采用UV-Vis、PL及PLE探究了 Sb2Te3 QDs的光学性质.研究表明:所制备的Sb2Te3 QDs平均粒径为2.3nm,平均高度为1.9nm,颗粒大小均匀、具有良好的分散性,PL与PLE峰位有明显的红移现象,研究还发现Sb2Te3 QDs在红外波段有明显的吸收与光致发光.研究表明:超声剥离法制备Sb2Te3 QDs是切实可行的,该量子点的PL与PLE对波长具有依赖性,其在红外波段的特性表明:它有望成为一种新型的红外探测材料.

Black phosphorus quantum dots (BPQDs) have recently obtained great attention due to their high mobility and tunable bandgap features, which are beneficial for their potential application in photoelectronic devices. However, a precise synthesis of high-quality BPQDs is still a great challenge owing to the formation of an impurity phase when employing traditional methods. Herein, we demonstrate the scalable fabrication of BPQDs from mineralization-derived bulk black phosphorus (BP) single crystals by means of a microwave (MW)-assisted liquid-phase exfoliation method in ethanol. The primary results demonstrate that ethanol plays a crucial role in determining the final properties of BPQDs, such as their excellent tolerance to oxygen, good crystallinity, and uniform size. Furthermore, the mechanism behind the formation of BPQDs is proposed, revealing that a layer-by-layer disintegration process of bulk BP crystals under microwave-energy stimuli is responsible. This work may provide a novel path for the further development of BPQDs and corresponding devices.

作为碳纳米材料家族的一员,碳量子点（CQDs）以其独特的光电特性、环境友好、制备成本低等优点成为近年来的研究热点,并在太阳电池、光电催化、传感器等光伏与光电领域展现出广阔的应用潜力。本文以壳聚糖为原料,采用水热法在酸性、中性、碱性（pH=3,7,10）环境下制备了荧光碳量子点,并对其光致发光性质和结构进行了表征。TEM测试表明,随着pH值从3增大到10,其粒径由2.80 nm减小到1.83 nm。将获得的碳量子点作为光敏化剂,组装成敏化太阳电池（SSCs）,结果表明pH=3时制备出的CQDs组装的太阳电池具有最高的光电转换效率（PCE）。为了进一步提升SSCs的性能,将CQDs与N719染料复合,制备了共敏化太阳电池（co-SSCs）。由于CQDs的上转换特性和良好的载流子传输性能,CQDs/N719基co-SSCs的PCE较CQDs及N719染料单独敏化太阳电池显著提高,最高PCE达9.13%。这些研究结果为制备碳量子点及组装高效敏化太阳电池提供了新思路。

In recent years, transition metal chalcogenides (TMDs) have attracted extensive attention of researchers due to their unique electronic structure and excellent photoelectric properties. In this paper, hexagonal structure 1T-ZrS2 quantum dots (QDs) having a monodisperse grain size of around 3.1 nm is prepared by the ultrasonic exfoliation method. The preparation includes the following steps: ZrS2 powder is ground, followed by ultrasonic exfoliation in 1-methyl-2-pyrrolidone (NMP), and 1T-ZrS2 QDs are collected after centrifugation. The structure, morphology and optical properties of the QDs are studied in detail. The structure, morphology, size distribution, and elemental composition of 1T-ZrS2 QDs are studied by using X-ray diffractometer (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The chemical bonds of 1T-ZrS2 QDs are characterized by X-ray photoelectron microscopy (XPS) and Fourier transform infrared spectrometer (FTIR). The TEM and AFM results show that the 1T-ZrS2 QDs are spherical in shape with uniform size distribution. The sizes of the 1T-ZrS2 QDs follow a Gaussian fitted distribution with an average diameter of WC = 3.1 nm and the FWHM is 1.3 nm. The XRD diffraction pattern of 1T-ZrS2 QDs show wide dispersed diffraction peaks, which is the characteristic of QDs. The diffraction peak at 2θ = 32.3° (d = 0.278 nm) corresponds to the (101) crystal plane, and the weak diffraction peak at 2θ = 56.8°(d = 0.167 nm) belongs to the (103) crystal plane. The grain size is also calculated by using the Debye-Scherrer formula, and the calculated value (2.9 nm) is consistent with the result of TEM (3.1 nm). Two Raman vibration modes (E1g and A1g) are observed. The E1g (507.3 cm–1) and A1g (520.1 cm–1) modes relate to the in-plane and out-of-plane vibration respectively. The Raman intensity of the A1g vibration mode is stronger than that of E1g. The UV-Vis and photoluminescence (PL and PLE) characterizations exhibit that the 1T-ZrS2 QDs have two UV absorption peaks at 283 nm and 336 nm, respectively. The Stokes shift is ~130 nm, the fluorescence quantum yield reaches up to 53.3%. The results show that the 1T-ZrS2 QDs have the excellent fluorescence performance and unique optical properties, which make the 1T-ZrS2 QDs an important material for developing photodetectors, multi-color luminescent devices, and other devices.

采用液相超声法首次成功制备出二硫化铼量子点(ReS2 QDs),表面形貌、物相组分和光学性能测试发现:ReS2 QDs平均粒径为2.7 nm,呈现六方晶系圆形结构并具有斯托克斯(Stokes)位移效应,表现出比体材料更优异的光学性能.

All-silicon tandem solar cells based on silicon quantum dots (Si-QDs) are considered to be one of the most promising high efficiency solar cells. In recent years, Si-QDs films with low Si-QDs density and many defects were reported. Thence, the photoelectric conversion efficiency of Si-QDs solar cells waslimited. Microwave Annealing (MWA) is considered to be a useful method to prepare nanostructured materials. The non-thermal effect of MWA can reduce energy for nucleation and improve the microstructure and photoelectric properties of the films. In this paper, SiCx thin films containing Si quantum dots were prepared via magnetron co-sputtering technique and MWA with different pulse power. The phase structure and spectral properties of Si-QDs films were characterized by grazing incidence X-ray diffraction (GIXRD), Raman, photoluminescence (PL) and spectrophotometer. The influence of different pulse power on the Si-QDs density and performance was studied systematically. Thin films with highdensity and good performance weredeposited by improving the magnetron sputtering process. The GIXRD and Raman spectra all showed that the Si-QDs existed in the samples, and their intensities first increased and then decreased. By Scherrer's formula, it was estimated that the size of Si-QDs increased initially and then decreased, and the maximum size of Si-QDs (7. 98 nm) wasobtained when the sputtering power was 80 W. The centers of Raman peaks areat 511 cm(-1). This is ascribed to Si-Si lateral optical vibration modeand its intensity is also increased first and then decreased. The optimum Gauss peak fitting was used for the Raman spectra. It showed that the crystalline fraction was higher than 62. 58%, and the highest crystallinefraction (79. 29%) was gained when the power was 80 W. The above analysis showed that Si-QDs formed in the films and the size of Si-QDs first increases and then decreases. The maximum number of Si-QDs was acquiredwith the power of 80 W. The optical bandgap was estimated by Tauc formula. These bandgaps were going to decrease and then increase with the increase of power. The bandgap reachedminimum value (17. 2 eV) with the power of 80 W. The Si-QDs size was inversely proportional to the band gap, indicating that the Si-QDs in the films had good quantum confinement effect. The luminescence properties of the samples were analyzed by the PL spectra, the optimum Gauss peak fitting was used. It was found that there were 6 luminescence peaks. Combine with the results of Raman spectrum, the luminescence peaks between 463 similar to 624 nm were derived from the role of the Si-QDs. The luminescence peaks between 408 and 430 nm originated from the defect state inside the films withoutthe shift of peak position, while the intensity varies. The distribution of the energy band gap were calculated according to the wavelength of the luminescence peak. Thus, the types of the defect state were determined, the luminescence peak at 408 nm is attributed to the electron radiation transition of Si degrees -> E-v, and the luminescence peak at 430 nm is attributed to Si degrees -> Si-Si defect state luminescence. The Si-QDs size on the luminescence peak shift was also studied. The results show that blueshift (redshift) of luminescence peak occurred with the size of Si-QDs becoming smaller (larger). In conclusion, SiC, films with Si-QDs prepared at the sputtering power of 80 W exhibited the best performance. The research results laid the foundation for the follow-up study of Si-QDs solar cells.

Although single-crystal black phosphorus (HP) can be prepared by the mineralization method, there have been few reports on the growth process of HP under non-vapor transport conditions. In this paper, a simple synthetic approach based on Sn-I-assisted mineralization is developed to produce high-quality orthorhombic single-crystal BP in a quartz tube. Through different temperature variations, we study the growth process of single-crystal BP under non-vapor transport conditions. The results show that by using the appropriate conditions, the mineralization method can be used to produce high-quality orthorhombic single-crystal HP. During the cooling process from 620 degrees C to 500 degrees C Hittorf 's phosphorus is formed. It is shown that 500 is a critical temperature for BP growth, which properly prolongs the holding time, promoting the growth of single-crystal HP. Finally, the growth process of BP under non-vapor transport conditions is clarified.