CdTeS_3量子点光阳极的制备与光电性能

将适量的碲、硫加入到硫化钠甲醇水溶液中反应生成Na_2TeS_3作为阴离子前驱体,以Cd(NO_3)_2为阳离子前驱体,通过连续离子层吸附与反应法(SILAR)制备CdTeS_3/TiO_2量子点敏化光阳极。采用拉曼光谱、X射线光电子能谱及能量色散X射线能谱分析表征了产物的价键结构和组成;通过紫外可见吸光光谱表征量子点的光吸收性能;利用J-V曲线与IPCE分别对CdS与CdTeS_3量子点敏化太阳能电池的光电性能进行了表征。实验结果表明,通过SILAR法制备的CdTeS_3量子点敏化太阳能电池能量转换效率比CdS量子点敏化太阳能电池能量转换效率高出约25%。     

离子层气相反应法制备CulnS2半导体薄膜

以CH3CH2OH为溶剂，CuCl和InCl3为反应物，H2S为硫源，用离子层气相反应法制备了CulnS2半导体薄膜。用X射线衍射、X射线光电子谱、扫描电镜和紫外-可见光谱等对薄膜的晶型、表面化学组成、表面形貌及光电性能进行了表征。分析了混合前驱体溶液中阳离子浓度比【Cu】／[In】对薄膜化学计量及性能的影响。[Cu]／[In]〉／1、25时，可获得黄铜矿结构的CulnS2薄膜，其单相形成区外【Cu】／叫为1．45-1．65。     

双喷头静电喷射法制备光滑且致密的二氧化硅薄膜

采用静电喷射法,用一个喷头喷洒四乙氧基硅烷(TEOS)与乙醇(Et OH)的混合溶液[n(TEOS)∶n(Et OH)=1.00∶19.00],另一个喷头喷洒乙醇、去离子水以及氨水(NH_3·H_2O)的混合溶液[n(Et OH)∶n(H_2O)∶n(NH_3·H_2O)=19.00∶0.90∶1.64],在溶液流速为60μL/min,喷头与基底之间的距离为10 cm,电压为12 k V的条件下喷洒1 min,在玻璃基底表面反应形成了光滑、致密的二氧化硅薄膜。采用扫描电镜与原子力显微镜对所得薄膜进行了表征。相比于使用单一喷头喷射前驱体溶液[n(TEOS)∶n(Et OH)∶n(H_2O)∶n(NH_3·H_2O)=1.00∶38.00∶0.90∶1.64]的传统方法,使用双喷头可以有效避免前驱体溶液在喷射前就生成二氧化硅小颗粒,从而提高了薄膜质量。通过考察基底温度对二氧化硅晶体生长的影响,发现薄膜的形成有明显的分形特征。     

超声喷雾热分解法制备p型氧化锌多晶薄膜

采用超声喷雾热分解法在玻璃衬底上以醋酸锌水溶液[Zn(CH3COO)2·2H2O]、醋酸铵(CH3COONH4)和硝酸铝[Al(NO3)3·9H2O]的混合溶液为前驱体生成了N-Al共掺P型氧化锌薄膜.考察了前驱体溶液浓度、载气流速、热解温度对实验结果的影响.用XRD和SEM测试手段对薄膜进行了晶体结构和表面形貌的表征,结果表明所制备的薄膜为六角纤锌矿结构的氧化锌薄膜,表面均匀,结构致密,具有强烈的呈c轴垂直于衬底的(002)择优取向.对薄膜进行了电学测试和光致发光性能测试,结果表明制备的薄膜为P型氧化锌薄膜,薄膜的光致发光明显具有氧化锌薄膜的特点.     

CdS/CuInS_2/TiO_2复合纳米薄膜光电性能的研究

利用连续离子层吸附反应(SILAR)法在Ti O2纳米棒阵列表面沉积生长了Cu In S2和Cd S量子点,采用FESEM表征了复合纳米薄膜的结构和形貌,采用紫外可见分光光度计和电化学工作站表征了薄膜的光学和光电性能。当Cu In S2和Cd S薄膜循环沉积次数均为5次时,薄膜的光电响应最强,光电响应程长为20μA/cm2。     

CdS/CdSe核壳结构半导体纳米晶结构及光谱特性

采用共沉淀法在水相中将CdS外延生长于CdSe半导体纳米晶(CdSe NCs)表面,制备了结晶形态较好的CdSc/CdS核壳结构半导体纳米晶(CdSe/CdS C/S NCs),并改善了CdSe NCs的荧光性能.通过X射线衍射,透射电镜和选区电子衍射分析证明了核壳结构的形成,并通过紫外可见光吸收光谱和荧光光谱分析证明了核壳结构对CdSe NCs荧光性能的改善.此外,实验结果表明:控制CdSe核合成中Cd前驱体溶液pH值能获得粒径分布较窄的CdSe/CdS C/S NCs;采用不同浓度比的Cd和Se前驱体溶液可以有效调节核壳结构半导体纳米晶的粒径;选择合适的CdSe与CdS摩尔比及壳层中Cd与S摩尔比能改善CdSe/CdS C/S NCs的荧光性能.     

连续离子层吸附反应(SILAR)法制备纳米Cu_2O薄膜

采用低温液相薄膜制备工艺--连续离子层吸附反应(SILAR)法,在玻璃衬底上制备了纳米Cu2O薄膜,考察了工艺参数对薄膜质量和薄膜表面形貌的影响,对薄膜的生长速率与反应溶液浓度、反应温度以及循环次数的关系进行了研究和分析。结果表明,采用连续离子层吸附反应(SILAR)法有利于制备高质量的纳米Cu2O薄膜,连续离子层吸附反应(SILAR)法可以有效去掉疏松的离子,每次循环吸附反应都能使紧密吸附的离子转化成致密的纳米Cu2O薄膜,这样既有利于纳米Cu2O颗粒的生成,同时减少了污染和降低了成本。试验表明,制备纳米Cu2O薄膜的最佳反应温度为70℃,最佳反应溶液浓度均为1 mol/L,纳米Cu2O薄膜的膜厚随着循环次数的增加而增加,循环40次可制得厚度为0.38μm的薄膜。经XRD和SEM测试,所制备的薄膜纯度高,表面平整且致密,Cu2O颗粒大小约为100 nm。     

浸渍离子层气相反应法制备CuInS2薄膜

以CH3CN为溶剂,CuCl2和InCl2为反应物,H2S为硫源,用浸渍离子层气相反应法制备CuInS2薄膜。研究混合前驱体溶液中Cu^2 与In^3 的离子浓度比[Cu^2 ]／[In^3 ]对薄膜晶体结构、化学组成、表面形貌、光学和电学性能的影响。当溶液中[Cu^2 ]／[In^3 ]在0．75～2．00范围内均可形成无杂质相、富S型立方闪锌矿结构的CuInS2薄膜。当[Cu^2 ]／[In^3 ]=1．50时,CuInS2薄膜接近其理想的化学计量组成．薄膜表面均匀性随着[Cu^2 ]／[In^3 ]的增加而降低。CuInS2薄膜的光吸收系数α均高于10^4cm^-1,其禁带宽度Ex在1．30～1．40eV之间。制备的P型CuInS2半导体薄膜在室温下其表面暗电阻ρ随[Cu^2 ]／[In^3 ]的增加而有明显的降低趋势。     

异质界面个数对PbZr_(0.52)Ti_(0.48)O_3/Ba(Mg_(1/3)Ta_(2/3))O_3薄膜铁电性能的影响

采用溶胶-凝胶法制备PbZr_(0.52)Ti_(0.48)O_3(PZT)薄膜前驱体溶液,采用水溶液凝胶法制备Ba(Mg_1/_3Ta_2/_3)O_3(BMT)薄膜前驱体溶液。研究了异质界面个数对PZT/BMT薄膜微观形貌、铁电性能的影响。在PZT/BMT薄膜中,PZT薄膜没有裂纹、结晶良好,界面个数的增加有利于PZT薄膜结构的致密。界面个数的增加可降低PZT/BMT薄膜剩余极化值和矫顽场。PZT/BMT薄膜在适当偏置电场下存在一个介电峰值,且正负偏置电场下的介电峰值不同,介电偏压特性曲线呈现不对称分布。采用二极管等效界面势垒和对薄膜电滞回线求导可有效解释介电偏压特性曲线不对称和介电峰值的差异。     

不同旋涂方式对铜锌锡硫硒薄膜及相应器件性能的影响

晶体质量是决定铜锌锡硫硒(Cu₂ZnSn(S,Se)₄, CZTSSe)吸收层薄膜吸收效率的关键,旋涂是溶液法制备CZTSSe吸收层的第一步,因此旋涂方式的选择至关重要。为了探究不同旋涂方式对CZTSSe吸收层薄膜质量和相应器件性能的影响,分别采用三组不同的旋涂方式制备铜锌锡硫(Cu₂ZnSnS₄, CZTS)前驱体薄膜及CZTSSe吸收层薄膜,并利用X射线衍射仪(XRD)、能谱仪(EDS)、显微拉曼光谱仪(Raman)、场发射扫描电子显微镜(FE-SEM)分析了不同旋涂方式对所制备的CZTSSe吸收层薄膜晶体结构、元素成分、相纯度、表面形貌的影响。同时,采用电流密度-电压(J-V)测试和外量子效率(EQE)测试对CZTSSe吸收层薄膜太阳电池的光电特性进行了表征。结果表明:旋涂7周期,且第一周期烘烤之前旋涂2次的效果最好,所制备的CZTS前驱体薄膜均匀,无裂纹,CZTSSe吸收层薄膜结晶度更高,薄膜表面更平整致密,晶粒大小更均匀,实现了9.63%的光电转换效率。通过对采用不同旋涂方式制备的器件的性能参数进行统计分析,得出新的旋涂方式可以提高CZTSSe薄膜太阳电池的可重复性,为将来可能的大规模商业化应用做铺垫。     

Structural and optical studies of CdS and CdS:Ag nano needles prepared by a SILAR method

Nano-crystalline CdS and Ag-doped CdS films are deposited on glass substrate by a SILAR technique at room temperature with cationic precursors of cadmium nitrate and silver nitrate, and anionic precursor of sodium sulfide with different S:Cd ratio in starting solutions. In order to fabricate samples, substrates were taken in the solutions with determined duration and immersion cycles. To investigate the structural and morphological characteristics of the samples XRD analysis and SEM were used. The X-ray diffraction patterns show that the CdS samples have cubic crystal structure with preferential orientation along the (111) plane and CdS:Ag samples have hexagonal crystal structure with preferential orientation along the (002) plane. Also the peak intensity of XRD patterns of CdS increases with increasing the number of immersion cycles. Optical reflection of the layers is measured with a spectrophotometer and their optical absorption coefficient and band gaps are calculated. The band gap energy of Ag-doped samples decreases respect to CdS samples. It seems that silver doping creates intermediate levels in the energy gap and this causes decreasing of energy gap. Making samples with different S:Cd ratio demonstrates that the sample with 3:1 ratio has highest peak intensity in the XRD pattern and best stoichiometry. It is also observed that with increasing S:Cd ratio, the band gap energy of the samples decreases.     

Effect of post-deposition annealing on the properties of ZnO films obtained by high temperature,micro-controller based SILAR deposition

The ZnO thin films were prepared by successive ionic layer adsorption and reaction (SILAR) method at elevated precursor temperature. The films were later subjected to post-deposition annealing at different temperatures. This annealing process was found to be beneficial as it improved the structural and optical properties of the films. The ZnO films obtained by SILAR were found to be polycrystalline with hexagonal crystal structure. The crystallite size of the films increased considerably after annealing. The annealed films also showed very high absorption in UV region with marginal change in band gap. Both the crystallite size and optical absorbance were found to increase proportionately with the annealing temperature.     

Investigation of multilayered quantum dot-sensitized solar cells with different Zn chalcogenide passivation layers

In the case of cadmium sulfide (CdS) and cadmium selenide (CdSe)-based quantum dot-sensitized solar cells (QDSSCs), the addition of a zinc sulfide (ZnS) passivation layer improves the solar cell performance. In this study, multilayered QDSSCs were fabricated using CdS and CdSe quantum dots prepared by successive ionic layer adsorption and reaction (SILAR) method. The optimized QDSSCs were used to study the passivation effect of zinc chalcogenide layers: ZnS, zinc selenide (ZnSe), and zinc telluride (ZnTe). The best performing solar cell prepared from four SILAR cycles of CdS followed by six SILAR cycles of CdSe were used for subsequent deposition of Zn chalcogenide layers. It was observed that capping with ZnSe or ZnTe layer on the multilayered Cd chalcogenide QDs did not improve the solar cell performance. Only the addition of ZnS layer contributed to the better performance of the solar cell. The efficiency obtained in the optimized multilayered CdS/CdSe QDSSC with ZnS layer was 1.37 %, while the QDSSC with ZnSe or ZnTe capping showed lower performance. The behavior of the solar cells is explained with electrochemical impedance spectroscopy study.     

A Promising Modified SILAR Sequence for the Synthesis of Photoelectrochemically Active Cu2ZnSnS4 (CZTS) Thin Films

A promising modified SILAR sequence approach has been employed for the synthesis of photoelectrochemically active Cu₂ZnSnS₄ (CZTS) thin films. To study the influence of sulfurization temperatures on the CZTS thin films, the CZTS precursor thin films were annealed at temperatures of 520, 540, 560, and 580 °C for 1 h in an H₂S (5 %)+Ar (95 %) atmosphere. These films were characterized for their structural, morphological, and optical properties using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and UV-vis spectrophotometer techniques. The film sulfurized at an optimized temperature of 580 °C shows the formation of a prominent CZTS phase with a dense microstructure and optical band gap energy of 1.38 eV. The photoelectrochemical (PEC) device fabricated using optimized CZTS thin films sulfurized at 580 °C exhibits an open circuit voltage (V_oc) of 0.38 V and a short circuit current density (J_sc) of 6.49 mA cm⁻², with a power conversion efficiency (η) of 0.96 %.     

Nanocrystalline ZnO Thin Film Synthesis Using Glycerol in Aqueous Polymeric Precursor Processing

Synthesis of high-quality ZnO thin films via simple and cost effective processing technique is a major challenge. In this work, the preparation of nanocrystalline ZnO thin films by a novel polymeric precursor processing using glycerol as chelating agent is presented. The process has advantages of being cost-effective and environment friendly. ZnO thin films were prepared by a single spin-coating deposition of aqueous polymeric precursor prepared with zinc nitrate [Zn(NO₃)₂] and glycerol as chelating agent. The thermal decomposition of polymeric precursors was studied by thermogravimetric analysis and Fourier transform infrared (FTIR) spectroscopy. Annealing of these films were performed over the range of 300°–600°C, and the effect of annealing on the degree of crystallization, surface morphology, crystallite size, and optical properties was investigated. X-ray diffraction analysis shows that the thin films are polycrystalline with wurtzite structure. The thin films are 80% dense, have crack free microstructure, and transparency of >85% in the visible region. These films exhibit absorption edge at 375 nm. On measuring at room temperature, the optical band gap energy of ZnO thin films, annealed at 450° and 600°C, was determined to be 3.295 and 3.267 eV. Room temperature photoluminescence spectra of these films show strong UV emission and a broad yellow-green emission in the range 525–600 nm. The intensity of UV emission peak increases with increase in annealing temperature that is attributed to an improvement in crystallinity.     

Incorporation of zinc into calcium silicate hydrates, Part I: formation of C-S-H(I) with C/S=2/3 and its isochemical counterpart gyrolite

We have investigated the incorporation of zinc into both nanocrystalline and crystalline calcium silicate hydrates with starting C/S ratios of 2/3 (0.66). Zinc was added replacing calcium in the starting mixtures [Zn/(Zn+Ca)=0-1/4; 0-10 wt.% Zn], and the resultant phases were characterised using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), differential thermal analysis-thermogravimetry (DTA-TG) and environmental scanning electron microscopy (ESEM).In both groups of samples, increasing zinc content led to gradual structural changes, until eventually a second phase was formed. Zinc was incorporated to similar limits in both sets of samples. The thermal stability of the structures increased to a certain zinc content, beyond which there was structural destabilisation. Zinc incorporation is possible up to ∼6 wt.%. Our observations strongly indicate similar zinc incorporation mechanisms in both sample series, namely incorporation of zinc into the interlayer of C-S-H(I) and the X-sheet of gyrolite for nanocrystalline and crystalline samples, respectively.     

Preparation and Characterization Studies of Nanostructured CdO Thin Films by SILAR Method for Photocatalytic Applications

This work reports the preparation of cadmium oxide (CdO) thin films with different molar concentrations on glass substrate by simple and low cost SILAR (Successive Ionic Layer Adsorption and Reaction) method. The characterization, XRD pattern confirmed the presence of polycrystalline CdO in the deposited thin films with the cubic structure. The surface morphology and elemental composition of prepared thin films have been examined by scanning electron microscopy equipped with energy dispersive X-ray (EDX) analysis system. The optical property of the films was analyzed by UV–visible spectroscopy. The band gap of the deposited thin films was estimated by Tauc’s plot and it was found to be 2.6–2.8 eV. The prepared thin films were examined for the decomposition of the Methylene Blue (MB) dye which was visualized by UV-Visible spectroscopy, by decreasing the intensity of absorbance and concentration.     

The effect of chelating reagents on the layer-by-layer formation of CdS films in the electroless and electrochemical deposition processes

Triethanolamine (TEOA) and cysteine (Cys) were examined for the effect of chelating reagents to deposit CdS thin films by means of two different processes. Those are the successive ionic layer adsorption and reaction (SILAR) method and the successive under potential deposition (UPD) method, in which Cd and S are separately deposited on a polycrystalline Au substrate from each solution. Evaluation by stripping voltammetry showed that the amount of the deposited CdS was increased for 1, 3, 5, 7 and 10 layers of CdS prepared by these methods. It was found that, with the SILAR method, the order of the ability to increase CdS deposition was Cys>TEOA>none. On the other hand, with the successive UPD method, the order was none≥TEOA>Cys, showing a certain inhibition in the electrochemical deposition process. It is concluded that CdS deposition by the SILAR method becomes compatible to the successive UPD when a suitable chelating reagent was added to the Cd solution.     

Tuning PL emission energy and bandgap with Ni dopant of MgO thin films

In this study, for the first time, the effect of Nickel (Ni) additive on Magnesium oxide (MgO) thin films produced by using successive ionic layer adsorption and reaction technique (SILAR) was investigated. Absorption, photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) measurements were executed to examine how the optical, structural and morphological properties of the samples were affected by the addition of Ni. In the absorption analysis, it was noted that the band gaps of the MgO samples decreased from 4 eV to 3.5 eV with the increase of Ni dopant concentrations. Also, the transmittance values of MgO nanostructures decreases with the increase of Ni contribution, and in the same way, the reflection measurements show that the reflection of MgO decreases with the increase of Ni doping. PL measurements revealed that the fabricated structures radiate around 410 nm and 730 nm. According to XRD measurements, besides the cubic structure of the samples, NiO formations were detected inside the MgO thin film samples due to the increase in Ni dopant. XPS measurements have proven the presence of Ni doping in MgO. SEM measurements showed that all samples exhibited nanowall structure. All these results demonstrate that Ni doping on MgO thin films can be achieved by using SILAR deposition technique.     

Synthesis of MgO thin films grown by SILAR technique

Different thickness MgO thin films were grown on the glass substrate by successive ionic layer adsorption and reaction (SILAR) method as the first study in literature. X-ray diffraction (XRD) measurements demonstrate the cubic MgO structures and samples have (002), and (220) peaks. All film has nanoball structures observed from the scanning electron microscope (SEM) images. The band gap and transmittance values of MgO thin films decrease with increasing thickness. The photoluminescence (PL) spectrum demonstrates that samples have three visible emissions changing with thickness at 381?nm violet emission, 457?nm blue emission and 535?nm green emission. X-ray photoelectron spectroscopy (XPS) spectrum present confirms the elemental signals from carbon (C), oxygen (O) and magnesium (Mg) atoms in the sample. Both Moss and Herve and Vandamme relations refractive index values n, ε₀, and ε_∞ values and amount of oxygen increase with raising thickness of MgO thin films.