碘三离子后处理对钙钛矿太阳电池的影响研究

采用碘三离子(I₃^-)作为提升钙钛矿太阳电池性能的界面修饰材料，对钙钛矿体相及上层空穴传输材料的接触界面进行修饰和改性，钝化光活性层上表面缺陷，以优化光电转换器件的转换效率。由反溶剂法和后处理的形式，制备平面异质结电池，运用该界面钝化策略改善后的器件效率达到18.9%，且电池的稳定性也得到增强，600 h后仅有5%的性能衰减。通过物相和光电性质等表征与测试，系统地研究电池的形貌及性能参数，探究不同浓度的I₃^-对器件性能的影响作用和机理。研究发现，该缺陷钝化策略对钙钛矿膜层进行处理后，能有效改善钙钛矿材料的结晶性，减少其表面陷阱态缺陷，降低钙钛矿与空穴传输层的载流子界面传输势垒，且I₃^-与钙钛矿能形成钝化层，起到隔绝水氧的作用，使其稳定性得到改善。     

基于不同类型全无机钙钛矿材料的太阳能电池研究

随着新型光伏电池的发展,卤族钙钛矿太阳能电池备受关注,其中全无机钙钛矿材料因其良好的热稳定性、高吸光系数、带隙可调、制备工艺简单等优点,在光电和光伏器件领域具有良好的应用前景,基于全无机钙钛矿太阳能电池的最高效率达到了20.4%。本文总结了基于ABX₃、A₂BX₆、A₂B¹⁺B³⁺X₆以及类钙钛矿材料等全无机钙钛矿太阳能电池的光电转换效率及稳定性的对比,并着重分析造成效率和稳定性差异的影响因素及优化改良方法,最后对全无机钙钛矿太阳能电池材料面临的挑战进行了展望。     

加热和水处理共同调控PbI2薄膜形貌及其在钙钛矿太阳电池中的应用研究

该文研究加热和水处理共同作用对PbI₂薄膜形貌的调控和对钙钛矿太阳电池性能的影响。使用的钙钛矿体系为（FAPbI₃）_1-x（MAPbBr₃）_x,并在两步法工艺基础上对PbI₂薄膜进行不同时间加热和短时间水处理可将PbI₂薄膜制备成多孔结构。将双重处理后的PbI₂薄膜制备成钙钛矿薄膜后,可发现钙钛矿薄膜质量明显提升,表现在：钙钛矿的晶粒尺寸明显增大、结晶性增强、吸光能力提升、载流子传输更快。且此种方式能有效调控钙钛矿薄膜中的PbI₂残留量。在器件效率方面,只对PbI₂薄膜进行加热处理制备的电池的开路电压、短路电流、填充因子和效率分别为1.05 V、23.12 mA/cm²、73.81%和17.92%,而在最优双重处理工艺下制备的电池的这4个相应的参数分别为1.09 V、24.75 mA/cm²、77.85%和21.10%。     

Preparation of LiNi0.80Co0.15Al0.05O2 cathode material via Li-rich method

本文采用共沉淀法制备球形Ni_0.80Co_0.15Al_0.05(OH)_2.05前驱体,经预氧化后,采用富锂配比在氧气和空气气氛下烧结合成LiNi_0.80Co_0.15Al_0.05O₂正极材料.用X射线衍射,扫描电镜和恒电流充放电测试等方法对该材料的结构,形貌及电化学性能进行表征.结果表明:当锂配比为1.15时,氧气和空气中烧结合成的LiNi_0.80Co_0.15Al_0.05O₂正极材料的形貌,结构和电化学性能相当.富锂配比方法可在空气气氛下制备出电化学性能优异的LiNi_0.80Co_0.15Al_0.05O₂正极材料.0.1 C放电克比容量在200 mA·h/g以上,首次效率在87%左右;1 C放电克比容量在168 mA·h/g以上;800周循环容量保持率在80%以上.     

铁系无机材料用于新能源电催化硝酸盐还原制氨

硝酸盐是一类普遍存在的环境污染物,而其对应的还原态氨却是重要的化工原料和农业肥料。因此,探索将两者直接结合的化学转化具有重大的技术及经济战略意义,尤其是对当今“双碳”战略驱动下的高碳排放合成氨的工艺变革以及氨可能成为下一代载氢燃料。通过电催化技术,将硝酸盐还原合成氨过程与可再生能源电力结合,构建绿色低碳的含氮化学品人工“氮循环”的新循环技术与经济体系,是解决目前合成氨工业对化石能源高度依赖、高碳排放问题以及开发新氢能的有力途径。借鉴传统合成氨催化广泛应用、具有成本优势的铁系催化机制,分别选取单质Fe、Fe₂O₃和Fe₃O₄作为电催化材料,探索并揭示电催化硝酸盐还原合成氨催化反应的化学形态。结果表明：在相对于可逆氢电极电势为 -0.53 ~ -0.93 V区间内,Fe₂O₃表现出了最优异的催化活性,其生成氨的法拉第效率（FE_NH3）最高可达88%,对应的生成氨电流密度（J _NH3）为43.1 mA/cm²、氨生成速率（r_NH3）为0.20 mmol/(cm²·h)。此外,从控制硝酸盐转化率选择性获得氨和硝酸铵两种不同产物的技术路线,分析对比了相应的用电成本以及产品市场价格,充分说明了路线的经济性,说明铁系无机材料在电催化硝酸盐还原合成氨方面具有非常巨大的市场化潜力。     

低温固体氧化物燃料电池SDC-(Li/Na)2CO3复合电解质材料优化

采用两种工艺(干法和湿法)制备了钐掺杂的氧化铈(SDC)-(Li/Na)2CO3复合电解质,其中碳酸盐的质量分数分别为20%、25%和30%.通过XRO和SEM观察了不同制备工艺和碳酸盐含量的复合电解质材料的物相结构和表面形貌.采用交流阻抗法测量了复合电解质在空气中400～600℃温度范围的电导率.采用于压法制作了基于(SDC)-(Li/Na)2CO3电解质的单电池,并在氢气/燃料中评价了该电池的输出性能.     

体相异质结钙钛矿太阳电池的稳定性

钙钛矿太阳电池的光电转换效率取得了硅太阳电池的水平,然而制约其产业化发展的主要瓶颈是稳定性.为探索其衰减的物理规律,使用新两步连续沉积方法成功的制备了体相异质结钙钛矿太阳电池,其光电转换效率为6.73％.这种方法解决了传统两步法钙钛矿薄膜不均匀和相互扩散两步法反应不完全的缺点.将体相异质结钙钛矿太阳电池放在空气中10、20和80 min时对其稳定性进行测试,发现其光电转换效率会逐渐降低,它的开路电压几乎不变,它的短路电流密度和填充因子逐渐减小.通过交流阻抗测试进一步证实其衰减的主要原因是钙钛矿太阳电池的复合电阻和载流子寿命不断减小.主要原因可能钙钛矿材料在晶界处吸收空气中的水分和氧气,导致其分解.     

钙钛矿型BaFeO_(3-δ)载氧体的制备与气化性能

以柠檬酸作为络合剂,采用溶胶-凝胶法制备钙钛矿型BaFeO_(3-δ)载氧体,通过对产物进行XRD、TGDSC分析和固定床实验,考察了前驱液pH值及柠檬酸用量、热处理温度和煅烧气氛对产物物相的影响。结果表明,配制前驱液pH值为8、柠檬酸与金属硝酸盐摩尔比为1.5∶1时,凝胶内金属阳离子均匀性最好、产物中杂相最少;前驱体内有机物在285℃下可充分反应并释放大量气体,750℃煅烧最适合钙钛矿晶相形成;马弗炉煅烧产物内钙钛矿晶格含较多氧空位,氧空位的存在提高了生物质气化的碳转化率和合成气产率。     

Synthesis of LiNi0.8Co0.2O2 cathode material through sintering in an air environment and electrochemical properties characterization

制备锂离子电池正极材料LiNi_0.8Co_0.2O₂通常需要在纯氧气气氛下进行烧结.本工作以硫酸镍,硫酸钴和氢氧化钠为原料,采用并流共沉淀法制备了高密度Ni_0.8Co_0.2(OH)₂前驱体,再采用高温固相反应法在空气中烧结制备了锂离子电池LiNi_0.8Co_0.2O₂正极材料.采用X射线衍射(XRD),扫描电镜(SEM),恒流充放电测试(ECT),循环伏安(CV)与比表面积(BET)测试等方法对目标样品进行了表征,详细考察了烧结条件对材料结构,微观形貌及电化学性能的影响.结果表明,锂/(钴+镍)摩尔比为1.13∶1时,在管式炉中和空气气氛下于第一段烧结温度700 ℃保温9 h,于第二段烧结温度750 ℃保温12 h,合成的材料比表面积适中(0.78 m²/g),具有规则的六边形α-NaFeO₂层状结构,晶粒分布均匀,电化学性能最优.在0.5 C充放电倍率下和2.7~4.3 V电压范围内,其首次放电比容量达到153.0 mA·h/g,循环20次后放电比容量仍为150.7 mA·h/g,容量保持率达到98.5%,显示了优异的循环稳定性能,可用做高能量密度动力电池正极材料.     

Based on the materials genome of all solid state lithium ion battery realized national project

2011年6月美国启动“材料基因组计划”（Materials Genome Initiative,MGI）,变革了材料的研究与开发方式,大大加速新材料的发现,提高了材料从发现到应用的速度。我国于2016年启动首批 “材料基因工程关键技术与支撑平台重点专项”国家重点研发计划,其中,“基于材料基因组技术的全固态锂电池及关键材料研发”于2016年8月获得审批通过正式立项。北京大学深圳研究生院潘锋教授为负责人联合国内11家单位申请该项目并获得资助。该项目将开展材料基因组高通量计算、高通量制备和高通量检测等技术研究,并运用材料基因组技术指导和加速全固态锂离子电池及关键材料的研发,开发全固态电池样机,从根本上解决锂离子电池安全性问题。     

喷涂法制备混合阳离子钙钛矿太阳电池

采用热基底喷涂法分别制备了FA_0.85MA_0.15PbI₃和(FAPbI₃)_0.85(MAPbBr₃)_0.15两种混合阳离子钙钛矿薄膜,对两种薄膜进行了扫描电镜（SEM）、X-射线衍射（XRD）、紫外-可见光吸收光谱（UV-Vis）测试表征。结果表明,该方法制备的混合阳离子钙钛矿薄膜平整致密,FA_0.85MA_0.15PbI₃结晶性更好,并且吸收带边和吸收强度更大。将两种薄膜组装成平板太阳能电池,对电池的光电性能和稳定性进行了分析。结果表明,FA_0.85MA_0.15PbI₃ PSCs光电转换效率为13.21%,(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs光电转换效率为12.08%,并且(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs在放置80 d后,性能基本无变化,表明喷涂法制备(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs具有较好的稳定性。     

Synthesis and characterization of CuInSe2 thin films from Cu, In and Se stacked layers using a closed graphite box

Various techniques have been used to produce CuInSe₂ but the problem of producing films with the desired properties for efficient device fabrication over large areas has always persisted. The Stacked Elemental Layer (SEL) technique has been demonstrated as a method for producing films over a large area, but the films normally annealed in vacuum or in Se ambient, mostly exhibited poor morphology with small grain sizes which result in poor devices. A method of synthesizing CuInSe₂ films by annealing or selenization of the Cu, In and Se elemental layers using a closed graphite box was developed. SEM, EDX, XRD, spectrophotometric and Hall measurements were used to characterize all annealed films. Results have shown single phase chalcopyrite films with improved crystal sizes of about 4 μm The film composition varied from Cu-rich to In-rich with electrical resistivities of 10⁻³ to 10⁴ Ωcm, cattier concentrations of 5 × 10¹⁵ to 10¹⁷ cm⁻³ and mobilities of 0.6 to 7.8 cm² V⁻¹ s⁻¹ An energy band gap of 0.99 eV and 1.02 eV was obtained for a Cu-rich and near stoichiometric In-rich films respectively. Heterojunction devices using the structure ZnO/CdS/CuInSe₂ were fabricated with electrical conversion efficiencies of 6.5%.     

Optical and electrochemical characteristics of niobium oxide films prepared by sol-gel process and magnetron sputtering A comparison

Electrochromic niobia (Nb₂0₅) coatings were prepared by the sot-gel spin-coating and d.c. magnetron sputtering techniques. Parameters were investigated for the process fabrication of sol-gel spin coated Nb₂0₅ films exhibiting high coloration efficiency comparable with that d.c. magnetron sputtered niobia films. X-ray diffraction studies (XRD) showed that the sot-gel deposited and magnetron sputtered films heat treated at temperatures below 450°C, were amorphous, whereas those heat treated at higher temperatures were slightly crystalline. X-ray photoelectron spectroscopy (XPS) studies showed that the stoichiometry of the films was Nb₂0₅. The refractive index and electrochromic coloration were found to depend on the preparation technique. Both films showed low absorption and high transparency in the visible range. We found that the n, k values of the sot-gel deposited films to be lower than for the sputtered films. The n and k values were n = 1.82 and k = 3 × 10⁻³, and n = 2.28 and K = 4 × 10⁻³ at 530 urn for sot-gel deposited and sputtered films, respectively. The electrochemical behavior and structural changes were investigated in 1 M LiC10₄/propylene carbonate solution. Using the electrochemical measurements and X-ray photoelectron spectroscopy, the probable electrode reaction with the lithiation and delithiation is Nb₂O₅ + x Li⁺ + x e⁻ ↔ Li_xNb₂0₅. Cyclic voltametric (CV) measurements showed that both Nb₂0₅ films exhibits electrochemical reversibility beyond 1200 cycles without change in performance. “In situ” optical measurement revealed that those films exhibit an electrochromic effect in the spectral range 300 < λ < 2100 nm but remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for 250 nm thick electrodes. Spectroelectrochemical measurements showed that spin coated films were essentially electrochemically equivalent to those prepared by d.c. magnetron sputter deposition.     

染料敏化太阳能电池光阳极的优化与性能研究

对染料敏化太阳能电池（DSSC）光阳极的制作工艺进行优化设计,在光阳极初始默认的制作工艺条件下,分别对影响DSSC光电性能的光阳极活性面积、TiO₂薄膜厚度、是否添加散射层、TiO₂薄膜烧结温度、化学处理方法和TiCl₄浓度影响因素逐一进行考察,最终确定了光电极的最佳制作工艺：光阳极活性层面积为0.4 cm × 0.4 cm,TiO₂薄膜厚度为19 μm,并加散射层,TiO₂薄膜电极的烧结温度为T₁ = 525℃、二次烧结温度为T₂ = 500℃,采用0.1 mol/L的TiCl₄水溶液进行化学处理,获得短路电流密度19.45 mA/cm²,光电转换效率8.42%。此制作工艺方法简单、光谱特性好、光电转换效率高,有利于DSSC的结构优化与推广应用。     

CuInS2 based thin film photovoltaics

A fabrication process for CuInS₂ thin film solar cells, based on sulfurization of Cu/In bilayers, is described. The process is investigated by in situ energy dispersive X-ray diffraction for phase identification as a function of process time. It is found that Raman spectroscopy is very convenient and reliable in assessing the quality of CuInS₂ produced by this sequential process. Good quality CuInS₂ films efficiently collect charge carriers generated by the incident sunlight. The solar-to-electric conversion efficiency limitations of state-of-the-art CuInS₂ based devices are discussed using a comparison with device simulation. The module design is laid down and arguments for the up-scaling potential of this new type of solar cell are presented.     

Defect reduction in electrochemically deposited CdS thin films by annealing in 02

Using the electrochemical deposition method, CdS thin films were deposited from acid solutions (pH = 2.5) containing CdS0₄ and Na₂S₂0₃ on indium-oxide coated glass substrates. These films were annealed in N₂, air, or O₂ atmosphere at 200–500°C for 30 min. Photoluminescence spectra were measured at 77 K. For the films annealed in N₂, the band edge emission became weaker and the luminescence due to defects shifted to longer wavelengths as the annealing temperature was raised above 300°C. However, for the films annealed in air or O₂, the band edge emission was observed strongly irrespective of the annealing temperature and the luminescence due to defects was weak. Thus the O₂ annealing is useful for the defects reduction.     

Characterization of Cu(InxGa1−x)2Se3.5 thin films prepared by rf sputtering

Cu(In_xGa_1−x)₂Se_3.5 thin films were fabricated by rf sputtering from CuIn_xGa_1−xSe₂ and Na mixture target by controlling the mixture ratio. X-ray diffraction analyses show that the structure of Cu(In_xGa_1−x)₂Se_3.5, thin films is different from chalcopyrite structure: especially, CuIn₂Se_3.5 thin films have a defect chalcopyrite structure. The lattice parameters for Cu(In_xGa_1−x)₂Se_3.5 thin film are slightly smaller than those for CuIn_xGa_1−xSe₂ thin film and linearly decreased with increasing Ga content. The optical absorption coefficients for Cu(In_xGa_1−x)₂Se_3.5, thin films exceed 2 × 10⁴ cm⁻¹ in energy region above the fundamental band edge. The band gap for Cu(In_xGa_1−x)₂Se_3.5 thin films is larger than that for CuIn.Ga_1−x2Se₂ with the same Ga content and increased with increasing Ga content.     

Composition control of electrodeposited Cu---In---Se layers for thin film CuInSe2 preparation

Electrodeposition of Cu-In-Se films has been studied with an aqueous solution containing CuCl₂, InCl₃ and SeO₂, in terms of composition control of deposited films for the preparation of CuInSe₂. From the relationship between In/Cu or Se/Cu ratio in the bath and that in the deposited film, the ratio of mass-transfer coefficients for In and Cu, k(In)/k(Cu) or for Se and Cu, k(Se)/k(Cu), has been obtained and their dependences on deposition current density or stirring of the solution have been studied. The rate-determining step in the deposition process, reaction or diffusion, has been also discussed. By employing the stirring, a remarkable improvement, by a factor of 3, is attained for run-to-run and position-to-position fluctuation of In/Cu ratio in the films. X-ray diffraction patterns show that CuInSe₂ is contained in as-deposited films.