Dy3+在Ba3La(BO3)3 中的光致发光

研究了Ba3La(BO3)3 基质中Dy3 的光致发光特性; 探讨了RE3 的电荷半径比(z/r)和Ce3 , Dy3 含量对Dy3 发光强度及发光颜色的影响; 分析了Ba3La(BO3)3 中Ce3 对Dy3 发光的敏化作用; 确定了Dy3 的 4F9/2→6H15/2及4F9/2→6H13/2跃迁发射的浓度猝灭机制均为电偶极-电四极相互作用.     

钙钛矿CH3NH3PbI3晶体的电化学

电化学方波伏安及循环伏安测量表明,钙钛矿CH₃NH₃PbI₃晶体在有机电解质中的氧化还原过程伴随着化学降解。该化学降解源于CH₃NH₃PbI₃晶体中铅离子的还原以及碘离子的氧化。通过电化学伏安法可以测定晶体的能带。     

LaVO3和NdVO3的合成

以Ｖ２Ｏ３为起始原料，在氩气中合成了ＡＢＯ３型稀土钒化合物，对加热前通氩气的时间，Ｖ２Ｏ３∶Ｌａ２Ｏ３的配比等进行了探讨，得到了适宜的制备条件。首次报道了ＬｎＶＯ３（Ｌｎ＝Ｌａ，Ｎｄ）的热学性质，发现ＬａＶＯ３具有吸附二氧化碳的特性。     

KMgF3:Ce3+,Tb3+纳米粒子中Ce3+→Tb3+的发光及能量传递

利用微乳液方法,合成了铈、铽共掺杂的氟镁钾纳米粒子,研究了体系中Ce3+→Tb3+的发光特性以及它们之间的相互作用,结果表明KMgF3:Ce3+Tb3+纳米粒子中存在Ce3+→Tb3+的能量传递过程,即Ce3+可以将吸收的能量直接传递给Tb3+离子,使得Tb3+的绿色发光强度大为增加.     

[{(C5Me4R)Ru}3Ru(η3-As3)(μ3,η3-As3)(μ3-As)3], arsenreiche Vierkerncluster

The interaction of [(η⁵-C₅Me₄R)Ru(CO)₂]₂ (1a: R = Me, 1b: R = Et) with yellor arsenic, As₄, affords besides the pentaarsaruthenocenes [(η⁵-As₅)Ru(η⁵-C₅Me₄R)] (2a, 2b) the tetranuclear clusters [{(η⁵-C₅Me₄R)Ru}₃Ru(η³-As₃)(μ₃,η³-As₃)(μ₃-As)₃] (3a, 3b). The structure of 2b and 3b has been elucidated by X-ray analysis.     

Non-Isothermal Kinetics of the Decomposition Reaction of Cluster [Ag3WS3Br]（PPh3）3 and [Cu3WS3Br]（PPh3）3

The thermal behaviors of clusters [Ag3WS3Br](PPh3)3 and [Cu3WS3Br](PPh3)3 (PPh3=triphenyl phosphine) in a nitrogen atmosphere were studied under the non-isothermal conditions by simultaneous TG-DTG-DSC and EDS techniques. The results showed that the evolution of PPh3 generally proceeded before the release of the other moiety in one or two step-mode. The mechanisms, the kinetic and the thermodynamic parameters for decomposition of PPh3 of both clusters were determined and calculated by jointly using several methods, which showed that its evolution was controlled by Avrami-Erofeev equation. The results also showed that there was no new stable phase composed of W-Ag(Cu)-S-Br after release of organic moiety PPh3 and that CVD method was not applicable to their further processing.     

有关NdCl_3·3ROH-AlEt_3催化体系的活性

<正> 我们曾指出,在NdCl_3·3ROH-AlEt_3体系中,醇的作用在于它的给电子性将会降低稀土离子的正电性,从而减弱Nd-Cl键的离子性,同时引起晶格的变化,使之有利于烷基化作用的发生,导致活性提高。本实验采用一种简便的方法证实了这种作用的发生。 这个方法所根据的原理是一般Ziegler-Natta型催化组分的熟知反应形式:     

紫外光辐照下CH3NH3PbI3基钙钛矿太阳能电池失效机制

随着光伏产业的不断发展,有机无机杂化钙钛矿太阳能电池的研发成为科学与工业界广泛关注的焦点。到目前为止,其光电转换效率已经提高到了25.2%,成为替代硅基太阳能电池的核心方案之一。然而,钙钛矿太阳能电池的稳定性较差,容易受到环境中氧气、水分、温度甚至光照的影响,这严重制约了其大规模推广与应用。大量科学研究表明,如何避免紫外辐照下有机无机杂化钙钛矿太阳能电池的性能衰减,对于提高钙钛矿太阳能电池的光照稳定性至关重要。然而到目前为止,仍然没有系统的工作来对紫外辐照下钙钛矿太阳能电池性能以及微结构演化过程进行详细的表征与分析。本文中,我们利用聚焦离子束-扫描电子显微分析(FIB-SEM)以及球差校正透射电子显微分析(TEM)等技术,全面地研究了紫外辐照过程中有机无机杂化钙钛矿太阳能电池性能变化规律以及电池微结构演化特征。实验结果表明,紫外辐照过程中太阳能电池内部会形成0.5–0.6 V的内建电场,钙钛矿中的I^-离子在电场的驱动下向金属Au电极和空穴传输层2, 2’, 7, 7’-四[N, N-二(4-甲氧基苯基)氨基]-9, 9'-螺二芴(Spiro-OMeTAD)一侧迁移;随后,空穴传输层与金电极的界面处,碘离子与光生空穴一起与金电极发生反应,将金属态Au氧化成离子态Au⁺。而Au⁺离子则在内建电场的驱动下反向迁移穿过钙钛矿MAPbI₃层,直接被SnO₂和MAPbI₃界面处的电子还原形成金属Au纳米团簇。除此之外,紫外辐照过程中钙钛矿太阳能电池性能降低的同时,往往伴随着Spiro-OMeTAD与钙钛矿界面处物质迁移、钙钛矿薄膜内晶界展宽以及Au纳米颗粒周围MAPbI₃物相分解等现象。以上各种因素的协同作用,共同导致了紫外光照下有机无机杂化钙钛矿太阳能电池光电转换性能(PCE)、开路电压(V_oc)以及短路电流(J_sc)等性能参数的急剧下降。     

簇合物〔WOS_3 Ag_3 Br(PPh_3)_3〕·(OPPh_3)的合成和晶体结构

报道了〔WOS3Ag3Br(PPh3) 3〕·(OPPh3)簇合物 (C72 H6 0 Ag3BrO2 S3P4W ,Mr=176 4.6 1)单晶的合成和结构。该晶体属于三方晶系 ,空间群为R3 ,晶胞参数 :a =16 .14 0 (3) ,c =2 3 .0 0 3(4) ,V =5 189.4(15 ) 3,μ(MoKα) =3 .2 98mm- 1 ,Z =3 ,F(0 0 0 ) =2 5 98,Dc=1.6 94g/cm3。独立衍射点 2 181,可观察衍射点 195 2 (I≥ 2σ(I) ) ,R =0 .0 496 ,wR =0 .12 48。该晶体由簇合物分子〔WOS3Ag3Br(PPh3) 3〕和以P为中心的扭曲四面体结构的中性分子OPPh3 构成 ,其中的簇合物分子的骨架为由1个W原子、3个S原子、3个Ag原子和 1个Br原子构成的立方烷状。W、O(1)和Br原子位于C3轴上。     

空气下光诱导有机金属卤化钙钛矿薄膜的降解机理

近几年来钙钛矿材料作为新兴光伏材料取得了巨大的发展进步,但有机无机杂化钙钛矿较差的环境稳定性限制了它的大规模应用。因此深入研究钙钛矿材料的降解机制有助于开发更稳定的钙钛矿光伏器件。本文基于透射电子显微学的微观形貌观察、晶体结构及元素成分表征,详细研究了杂化钙钛矿CH_3NH_3PbI_3薄膜在光照以及空气共同作用下的降解机理。研究发现,光诱导下CH_3NH_3PbI_3薄膜会与空气中的氧气发生交互作用,同时生成六方晶态PbI_2甚至氧化为非晶态化合物PbI_(2-2x)O_x (0.4 x 0.6),而其衰减位点主要存在于薄膜与空气接触的表面。降解过程中,由于存在着挥发性分解产物(I_2,CH_3NH_2)的大量丢失,薄膜的表面会产生许多小孔洞,继而形成一种蜂窝状的介孔衰竭通道。而这种衰竭方式主要与光照下钙钛矿中光生电子与氧气结合形成超氧根自由基(O_2~(·-))有关,该基团诱导了CH_3NH_3PbI_3向PbI_2和非晶氧化态的转变。本文揭示了空气中光照诱导钙钛矿薄膜的降解机理,这将为未来设计和优化更稳定的钙钛矿太阳能电池提供全面的实验数据与理论支持。     

两步沉积法制备Br或Cl掺杂的有机-无机杂化钙钛矿太阳电池

采用控制前驱体浓度的两步沉积法和插入PbI₂层的DMSO分子（PbI₂（DMSO）复合体）分别与MAX（MA=CH₃NH₃,X=I,Br）或MAX（X=I,Cl）进行的分子内交换法,实现了Br或Cl的掺杂并合成了厚度为300nm左右的混合卤化物钙钛矿MAPbI_3-xBr_x和MAPbI_3-xCl_x膜。MAX前驱体溶液中含5%（摩尔分数,下同）MABr或15% MACl所生成的Br或Cl掺杂钙钛矿膜能提高钙钛矿太阳电池的光伏性能,进一步提高MABr或MACl的含量并不会明显改变掺杂量,但会形成小的白色颗粒或者针孔,这些将对电池的性能产生不利影响。前驱体溶液含5% MABr的MAPbI_3-xBr_x钙钛矿太阳电池所获得的能量转换效率（PCE）为13.2%,含15% MACl的MAPbI_3-xCl_x钙钛矿太阳电池获得了最高13.5%的PCE。     

基于CH3NH3PbI3单晶的Ta2O5顶栅双极性场效应晶体管

Organic-inorganic hybrid perovskite methylammonium lead iodide (CH₃NH₃PbI₃) generally tends to show n-type semiconductor properties. In this work, a field-effect transistor (FET) device based on a CH₃NH₃PbI₃ single crystal with tantalum pentoxide (Ta₂O₅) as the top gate dielectric was fabricated. The p-type field-effect transport properties of the device were observed in the dark. The hole mobility of the device extracted from transfer characteristics in the dark was 8.7×10^-5 cm²·V^-1·s^-1, which is one order of magnitude higher than that of polycrystalline FETs with SiO₂ as the bottom gate dielectric. In addition, the effect of light illumination on the CH₃NH₃PbI₃ single-crystal FET was studied. Light illumination strongly influenced the field effect of the device because of the intense photoelectric response of the CH₃NH₃PbI₃ single crystal. Different from a CH₃NH₃PbI₃ polycrystalline FET with a bottom gate dielectric, even with the top gate dielectric shielding, light illumination of 5.00 mW·cm^-2 caused the hole current to increase by one order of magnitude compared with that in the dark (V_GS (gate-source voltage)=V_DS (drain-source voltage)=20 V) and the photoresponsivity reached 2.5 A·W^-1. The introduction of Ta₂O₅ as the top gate dielectric selectively enhanced hole transport in the single-crystal FET, indicating that in the absence of external factors, by appropriate device design, CH₃NH₃PbI₃ also has potential for use in ambipolar transistors.     

醋酸铅作为铅源合成CH3NH3PbBr3-xClx纳米晶体颗粒

Lead acetate, which is highly soluble in dimethylformamide, was used to synthesize mixed halide perovskite CH₃NH₃PbBr_3-xCl_x (MA = CH₃NH₃, 0 ≤ x ≤ 3) nanocrystals (NCs). This method provides an approach to address the low solubility of lead halides, especially lead chloride. Different Br/Cl ratios in MAPbBr_3-xCl_x lead to various optical properties. The photoluminescence emission peak can be tuned from 399 to 527 nm. Their full-widths at half-maxima (FWHM) are about 20 nm. MAPbBr_3-xCl_x NCs have an average diameter of ~(11 ± 3) nm and have uniform dispersion in toluene. The MAPbBr₃ NCs have a long average recombination lifetime (τ_ave = 97.4 ns) and a photoluminescence quantum yield (PLQY) of up to 73%.     

Molecular motion and phase transition in perovskite-type (CH3)nNH4−nSnCl3 (n=1–4) studied by proton NMR spin–lattice relaxation

Powder X-ray diffraction, ¹¹⁹Sn NMR spectra, and ¹H NMR spin–lattice relaxation times, T₁, were measured for (CH₃)_nNH_4−nSnCl₃ (n=1–4). From the Rietveld analysis, it is shown that all four compounds crystallize into deformed perovskite-type structures at room temperature. The temperature dependence of ¹H T₁ was analyzed in terms of the CH₃ reorientation and other motions of the whole cation. Except for the phase transition in CH₃NH₃SnCl₃, which is from monoclinic to rhombohedral at 331 K, ¹H T₁ was continuously changed at other phase transitions in this compound as well as in the n=2–4 compounds, suggesting that the transitions are not caused by the change of the motional state of the cation but by an instability of the [SnCl₃]_nⁿ⁻ perovskite lattice.     

少铅钙钛矿CH3NH3SrxPb(1-x)I3的合成及其在全固态薄膜太阳能电池中的应用

近年来, 有机-无机杂化铅卤化物钙钛矿太阳能电池(PSCs)得到了迅猛发展, 其最高光电转换效率已经达到19.3%. 该类型太阳能电池使用的钙钛矿型吸光材料为含Pb的有机-无机杂化铅卤钙钛矿, 从长远来看,Pb的毒性将制约其大规模应用. 本文从减少吸光材料中Pb的含量出发, 尝试用Sr 部分取代Pb制备一系列少铅钙钛矿CH₃NH₃Sr_xPb_(1-x)I₃, 并将其应用于钙钛矿太阳能电池进行光电性能的研究. 研究结果表明, 相比于全Pb 钙钛矿(CH₃NH₃PbI₃)材料, Sr 取代量为30% (x=0.3)时, 所形成的CH₃NH₃Sr_0.3Pb_0.7I₃光谱吸收大范围增强,但基于此材料制备的电池器件性能明显下降.     

PbO-PbI2复合物膜转化的CH3NH3PbI3钙钛矿薄膜及其光电特性

有机-无机卤化物钙钛矿是一类优异的光电材料. 在过去四年内, 基于有机-无机卤化物钙钛矿的光电器件实现了超过15%的光电转换效率. 而有机-无机卤化物钙钛矿材料的可控制备是保证其在光电器件中应用的基础. 本文采用新的沉积方法在玻璃衬底表面制备了一种典型的有机-无机卤化物钙钛矿CH₃NH₃PbI₃薄膜. 其制备过程是: 采用超声辅助的连续离子吸附与反应法在玻璃衬底表面沉积PbO-PbI₂复合物膜, 之后与CH3NH3I蒸汽在110 ℃环境下反应, 将PbO-PbI₂复合物膜转化成CH₃NH₃PbI₃钙钛矿薄膜. 对CH₃NH₃PbI₃薄膜的微观结构, 结晶性及其光电性能等进行了表征. 结果表明, CH₃NH₃PbI₃薄膜呈晶态, 具有典型的钙钛矿晶体结构. 薄膜表面形貌均匀, 晶粒尺寸超过400 nm. 在可见光范围, CH₃NH₃PbI₃薄膜透过率低于10%, 能带宽度为1.58eV. 电学性能研究表明CH₃NH₃PbI₃薄膜表面电阻率高达1000 MΩ. 高表面电阻率表明CH₃NH₃PbI₃薄膜具有一定的介电性能, 其介电常数(ε_r)在100 Hz时达到155. 本研究提出了一种制备高质量CH₃NH₃PbI₃钙钛矿薄膜的新方法, 所得CH₃NH₃PbI₃薄膜可望在光、电及光电器件中得到应用.     

两亲性季铵盐对钙钛矿太阳能电池效率和稳定性的影响

将廉价易得的两亲性季铵盐十六烷基三甲基溴化铵（CTMAB）加入到钙钛矿前驱体溶液中，通过调节添加量研究了CTMAB对钙钛矿太阳能电池效率和稳定性的影响.结果表明，加入CTMAB后制备的钙钛矿薄膜更加致密均匀，表面缺陷更少，钙钛矿晶体结晶性得到显著提高，从而提高了电池的光电转换效率及电池稳定性；含有CTMAB的钙钛矿太阳能电池的光电转换效率（PCE）为18.03%，明显高于未添加CTMAB的电池效率（17.05%）；含有CTMAB的电池稳定性有较大的提高，在一定湿度环境中保存40 d后效率仍达初始效率的95%，而未添加CTMAB的器件效率只有初始效率的70%.     

Anionic derivatives of pentafluoro-λ-sulfanyl (fluorosulfonyl) acetic acid esters

New ester salts [R₃NH]⁺[F₅SC(SO₂F)C(O)OR′]⁻ where RH, CH₃CH₂ and R′CH₃,(CH₃)₂CH have been prepared from corresponding esters and amines. The sodiumsalt Na[F₅SC(SO₂F)C(O)OCH(CH₃)₂] was used to prepare the following -substitutedderivatives: SF₅CX(SO₂F)C(O)OCH(CH₃)₂, XBr, Cl. The crystal structure of[(C₂H₅)₃NH]⁺[F₅SC(SO₂F)C(O)OCH₃]⁻ was determined and is monoclinic: P2₁/n;a=8.758(2) Å, b=9.645(2) Å and c=19.167(4) Å; β=97.92(3)°; V=1603.6 ų; Z=4.