Based on first-principle,the geometric structures of intrinsic SnS2 and SnS2 doped with Ti atom replacing Sn atom were constructed,and the adsorption characteristics of five gases,namely CO,NO2,NO,SO2 and NH3 on the surfaces of the two materials were analyzed.Three adsorption sites were tested for each gas molecule and the best adsorption site was determined.The adsorption energy,transfer charge,recovery time,density of states and work function were researched to understand the adsorption mechanism.It is found that the adsorption capacities of CO and SO2 on the intrinsic SnS2 are weaker,while the adsorption capacities of NO,NO2 and NH3 on the intrinsic SnS2 are stronger.The structure of SnS2 doped by Ti atom replacing Sn atom is relatively stable,and its formation energy is-8.028 eV.At the same time,the adsorption energies of the five gas molecules on their surfaces increase to different degrees.The results show that SnS2 doped by Ti atom replacing Sn atom can improve the gas adsorption performance of SnS2 material,and its preparation method is practical,so it can be considered as a material for making gas sensors.

研究不同扩散阻挡层对柔性钛衬底CZTSSe薄膜和电池性能的影响.X射线衍射(XRD)和拉曼光谱结果表明适当扩散阻挡层的引入可提高CZTSSe薄膜(112)择优取向和结晶性,还可抑制TiSe杂相的生成.CZTSSe结晶性的提高得益于扩散阻挡层表面较小的粗糙度.Cr、ZnO和TiN这3种不同阻挡层中,TiN层对TiSe杂相的抑制作用最强,用它作为扩散阻挡层制备的柔性CZTSSe薄膜结晶性最好,(112)晶面择优取向最强,电池性能最佳且转换效率相对无阻挡层电池提高了67％.

Cu 2 ZnSnS 4 (CZTS) thin films based on single-layer and double-layer prefabricated layer structure were prepared on substrates by two-step method. The influence of prefabricated layer structure on the surface morphology, element composition and photoelectric properties of CZTS thin film was studied. The crystal structure, surface morphology and composition of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The experimental results showed that the CZTS thin film with double-layer prefabricated structure had larger grain size, better crystallization and uniform distribution of film components than the CZTS thin film with single-layer prefabricated structure. The conversion efficiency of CZTS solar cells based on the double-layer prefabricated structure increased from 0.25% of the single-layer prefabricated structure to 3.05%. Therefore, the double-layer prefabricated structure CZTS thin film was more suitable as the absorption layer of CZTS thin film solar cells.

本文采用磁控溅射加后续硒化的方法制备柔性CZTSSe薄膜,通过向硒化气氛中引入钾元素实现了钾的有效掺杂.研究了钾掺杂量对柔性CZTSSe薄膜和电池性能的影响.X射线衍射和Raman结果表明适量掺入钾元素可以显著提高CZTSSe薄膜的(112)择优取向,增大晶粒尺寸,但钾元素掺杂量过高时又会使晶粒尺寸变小降低薄膜结晶性.另外钾元素的掺入也会改变CZTSSe/CdS间能带匹配情况,少量的钾元素掺杂对CZTSSe/CdS间导带失调值(CBO)影响不大,过量掺入钾元素则会明显增大CZTSSe/CdS间的CBO绝对值,进而降低柔性CZTSSe太阳电池转换效率.发现钾元素掺杂量为1.0μmol时,所制备的柔性CZTSSe薄膜平均晶粒尺寸超过1μm,且具有很强的(112)择优取向;制作的CZTSSe/CdS具有最佳的CBO数值,相应柔性太阳电池的最高值转换效率为3.06％.

Flexible CZTSSe solar cells were prepared on both thinned silicon substrate with and without nanopore array surface. The nanopore array structure could release thermal stress during the CZTSSe thin film preparation process, which improved the crystallization of CZTSSe thin film. The array structure could also absorb some bending stress during the bending test of CZTSSe solar cell, leading to obtaining a more reliable device. A flexible CZTSSe solar cell with only 14% efficiency loss after 3 times bending at 50mm radius was prepared by using nanopore array substrate.

In this research, a green and facile solution was reported by using ethylene glycol as solvent into Cu2ZnSn(S,Se)(4) thin films. Highly crystallized CZTSSe thin films without obvious impurity phases were obtained. We found that the carbon chains length of solvent has a notable influence on the of grain size distribution. Comparing the film obtained with 2-methoxyethanol solvent, CZTSSe thin film based on ethylene glycol had a thinner fine grain in the bottom layer and larger grains in the top layer. In addition, the CZTSSe thin film solar cell from ethylene glycol showed an obvious collection ability enhancement and an enhanced conversion efficiency by 45% than that from 2-methoxyethanol.

In order to improve the quality of B doped layer by diffusion,a novel boron source mixed with SiO2 nanosphere was introduced.Scanning electronic microscopy,four probe method and minority carrier lifetime measurement were adopted to study the influence of SiO2 nanosphere on the performance of p+ layer formed by B diffusion from boric acid solution.It was found that the thickness of boron rich layer (BRL) decreased from 130 nm to 15 nm compared with that produced without addition of SiO2 nanosphere.At the same time,the uniformity of diffusion increased from 88.17％ to 96.79％.In addition,junction depth decreased slightly and minority carrier lifetime in the samples increased apparently after using mixed boric acid solution with SiO2 nanosphere.All the results above indicated that SiO2 nanosphere could evidently enhance the property of the p+ layer formed by liquid B source diffusion from boric acid solution.

Aluminum nitride (AlN) thin film has broad application prospects due to its excellent physical and chemical properties and AlN film fabrication by the reactive magnetron sputtering method at low temperature is a hotspot of research work in recent years.AlN thin films were deposited at room temperature by DC magnetron sputtering with different N2 flow rates on p-type Si (100) wafer and slide glass substrates.The composition,microstructure,morphology and optical properties of AlN thin films were analyzed by the Fourier transform infrared (FTIR) spectrometer,X-ray diffractometer (XRD),scanning electron microscope (SEM) and spectrophotometer,respectively.The results show that the quality of films is improved with the increase of the N2 flow rate,and the obtained AlN thin films under 8 cm3/min N2are hexagonal wurtzite structure and an intense absorption peak exists at 680 cm-1 of wavelength in the FTIR spectrum,which further proves that the AlN films are successfully fabricated.The transmittance of AlN thin films is up to 94％ in the wavelength range of 300-900 nm.The optical band gaps of obtained AlN thin films become enlarged with the increase of the N2 flow rate and the maximum band gap is about 4.04 eV.

CdxZn1-xS thin films were prepared by chemical bath deposition in a solution containing cadmium chloride, zinc chloride, thiourea, sodium citrate and ammonia. The morphological, structural and optical properties of CdxZn1-xS films were investigated by X-ray diffraction, scanning electron microscopy, energy disperse spectroscopy and UV-vis-NIR spectroscopy. The photo-current response curves were also tested to study their electrical property. It was found that CdxZn1-xS thin films were successfully prepared at pH values from 10 to 13. With increasing of pH value, the ratio of zinc atom in the film and optical band gap decreased. All the films showed obvious photoconductive phenomenon. The CdxZn1-xS films prepared at pH = 11 and 12 showed uniform and dense surface morphology and presented good crystallinity. Their optical band gaps were about 2.92eV and 2.72 eV respectively, with light and dark conductivity ratio of 1.20 both. The photo-currents in the samples fell more quickly when the light was turned off, with current reduction of about 68.55% and 69.39% after 10s.

In this work we deposited a Ge thin layer under or upon Cu-Zn-Sn-S precursor by sputtering, followed by selenization process to obtain Ge doped CZTSSe thin films. A comparison of structural, morphology and optoelectrical property on Ge doped CZTSSe thin films with different Ge layer position was studied. It was found that even a little amount of Ge doping could affect the crystallization of CZTSSe grains. The solar cells based on two kinds of precursors both had VOC improvement compared with undoped CZTSSe solar cell. However, due to the inner stress in CZTSSe thin film, cracks appeared between the interface of buffer layer and window layer in CZTSSe solar cell with Ge bottom layer, leading to the decrease of conversion efficiency. With the help of Ge in reducing bulk recombination, CZTSSe solar cell based on Cu-Zn-Sn-S precursor with Ge top layer had a conversion efficiency of 5.38%, in contrast to 3.01% and 4.30% of CZTSSe solar cell with Ge bottom layer and undoped CZTSSe solar cell, respectively.

Flexible CZTSSe thin film solar cells were prepared on Ti foil substrate. With adding a Ge buffer layer between the Ti foil substrate and the Mo back contact, CZTSSe thin film showed a better crystallization and less secondary phases. It was confirmed that Ge diffused into CZTSSe layer and had a promoting effect on Sn+4 state formation and stress release. The flexible CZTSSe solar cell with Ge buffer layer showed a conversion efficiency of 2.00%, which presented a 200% enhancement comparing to the solar cell without Ge buffer layer. (C) 2016 Elsevier B.V. All rights reserved.

Ge-doped CZTSSe thin films were obtained by covering a thin Ge layer on CZTS precursors, followed by a selenization process. The effect of the Ge layer thickness on the morphologies and structural properties of Ge-doped CZTSSe thin films were studied. It was found that Ge doping could promote grain growth to form a compact thin film. The lattice shrank in the top-half of the film due to the smaller atomic radius of Ge, leading to the formation of tensile stress. According to thermodynamic analysis, Sn was easier to be selenized than Ge. Thus, Ge preferred to remain on the surface and increased the surface roughness when the Ge layer was thin. CZTSe was easier to form than Ge-doped CZTSe, which caused difficulty in Ge doping. These results offered a theoretical and experimental guide for preparing Ge-doped CZTSSe thin films for the potential applications in low-cost solar cells. With a 10 nm Ge layer on the top of the precursor, the conversion efficiency of the solar cell improved to 5.38% with an open-circuit voltage of 403 mV, a short-circuit current density of 28.51 mA cm-2 and a fill factor of 46.83% after Ge doping.

Effects of sulfurization pressure on structural and electrical property of Cu2ZnSnS4 (CZTS) thin film prepared by sulfurizing co-sputtered Cu–Zn–Sn–S precursor were investigated. X-ray diffraction patterns and Raman spectra confirmed the shrinkage of lattice and compressive stress forming in low pressure sulfurized CZTS thin film, which prevented the overgrowing of grains along vertical direction. In addition, low pressure sulfurization could reduce the number of small grains in film. Thus CZTS solar cell based on low pressure sulfurized CZTS thin film obtained a 124 % enhancement in conversion efficiency. Temperature-dependent conductivity measurement revealed the mechanism of the improvement in CZTS solar cell by low pressure sulfurization, which was due to the promotion of VCu forming and the removal of localized states in defect band.

Cu(InGa) Se-2 (CIGS) thin films were prepared using e-beam evaporation on a soda-lime glass substrate. The effect of substrate temperature and the difference between substrate temperature and post-annealing on the properties of the CIGS thin films and solar cells were studied. X-ray diffraction (XRD) and Raman spectroscopy, energy-dispersive spectroscopy, scanning electron microscopy, UV-Vis-NIR and the Hall effect were used to characterize the structural properties, composition, morphology, optical properties and electrical properties of the as-prepared CIGS thin films, respectively. The results demonstrated that the photoelectric properties of CIGS thin films prepared at a substrate temperature of 300 degrees C were optimal, with an efficiency of 7.1%. As the substrate temperature increased to over 300 degrees C, element gallium tended to evaporate from the substrate, which resulted in the variation of the Cu/(In + Ga) and Ga/(In + Ga) ratios of the films. The post-annealing process with in situ annealing temperatures of 300 degrees C and 400 degrees C was also studied. The results indicated that the post-annealing process, unlike the process of direct deposition at certain substrate temperatures, was able to avoid the element loss. At 300 degrees C in situ post-annealing temperature, there formed a 'polygon grains' Cu2-xSe phase, which disappeared when the in situ post-annealing temperature rose to 400 degrees C. The XRD patterns revealed that the post-annealing process made the element diffusion in films more uniform. The post-treated sample with an in situ post-annealing temperature at 400 degrees C, as a result, showed the highest efficiency of 9.0%, accompanied by the highest open-circuit voltage, short circuit current and fill factor.

研究了衬底温度对采用Cu2ZnSnS4靶和Cu靶共溅射制备的Cu2ZnSnS4薄膜晶粒生长的影响。采用拉曼光谱、X射线能量色散谱仪、扫描电子显微镜和紫外-可见-近红外分光光度计对在不同衬底温度条件下制备的Cu2ZnSnS4薄膜的元素比例、形貌以及光学带隙进行了表征与分析。结果表明制备的Cu2ZnSnS4薄膜晶粒生长遵循不同规律。室温衬底条件下制备的Cu2ZnSnS4薄膜晶粒生长遵循两步法，导致颗粒尺寸和元素分布不均；而在120~200℃衬底温度条件下制备的Cu-Zn-Sn-S预置层在溅射过程中已有Cu2ZnSnS4晶粒形成，这些晶粒在后续硫化生长过程中起到形核点的作用，促进了Cu2ZnSnS4晶粒的长大与元素的均匀分布。随着衬底温度的升高，Cu-Zn-Sn-S预置层及由此制备出的Cu2ZnSnS4薄膜的结晶性变好，Cu2ZnSnS4薄膜的带隙先升高后减小至1.55 eV。

Ideal amorphous carbon prepared at low temperature by e-beam evaporation has potential as buffer layers for Ge growth on Si.

CZTSSe thin films based on three-layer precursors with Cu-poor and Zn-rich in top and bottom layer while stoichiometric in middle layer were prepared. Compared with CZTSSe thin film obtained from a stoichiometric single layer precursor, the crystallization of thin film from a three-layer precursor got enhanced. Element distribution and growth nuclei position in precursor played an important role on CZTSSe thin film formation and solar cell performance. The conversion efficiency of CZTSSe solar cell from a three-layer precursor attained an increase of 3.54% over that from a single layer precursor.

室温下用射频磁控溅射法在玻璃和p型单晶硅衬底上沉积ITO薄膜,并对其进行不同温度的退火处理.采用XRD衍射仪测试薄膜结晶性,用紫外-可见分光光度计和霍尔效应测试试样光电性能,用吉时利2400表测试ITO/p-Si接触的I-V曲线,用线性传输线模型测试比接触电阻.研究结果表明:室温下沉积的ITO薄膜与p-Si形成欧姆接触,但比接触电阻较大.退火处理可以进一步优化接触性能,200℃退火后试样保持欧姆接触且比接触电阻下降为8.8×10-3 Ω·cm2.随着退火温度进一步升高到300℃,比接触电阻达到最低值2.8×10-3 Ω·cm2,但接触性能变为非线性.

The CZGexT1 -xS thin films were synthesized by sulfurizing the magnetron sputtered multi-layer met-al precursors (Zn /Ge /Sn /Cu)on glass substrate.The influence of the Ge-content on the microstructures and photo-electronic properties of the thin films was investigated with X-ray diffraction,scanning electron microscopy,Raman spectroscopy,ultraviolet-visible-near infrared (UV-Vis-NIR)spectroscopy and Hall effect measurement.The results show that the Ge-content significantly affect the photo-electronic properties of the CZGexT1 -xS.To be specific,as the Ge-content increased (x increased from 0 to 1),the grain size increased;the band-gap increased from 1.52 to 2.12 eV,possibly because an increasing number of Ge atoms substituted for Sn atoms,resulting in reduction of defect density in the CZGexT1 -xS coatings.In addition,the carrier concentration and mobility of the CZGeS coatings were found to be 1.99 ×1018 cm -3 and 9.712 cm2 /Vs,respectively.