High‐Purity Inorganic Perovskite Films for Solar Cells with 9.72 % Efficiency

All‐inorganic perovskite solar cells with high efficiency and improved stability are promising for commercialization. A multistep solution‐processing method was developed to fabricate high‐purity inorganic CsPbBr₃ perovskite films for use in efficient solar cells. By tuning the number of deposition cycles (n) of a CsBr solution, the phase conversion from CsPb₂Br₅ (n ≤3), to CsPbBr₃ (n=4), and Cs₄PbBr₆ (n≥5) was optimized to achieve vertical‐ and monolayer‐aligned grains. Upon interfacial modification with graphene quantum dots, the all‐inorganic perovskite solar cell (without a hole‐transporting layer) achieved a power conversion efficiency (PCE) as high as 9.72 % under standard solar illumination conditions. Under challenging conditions, such as 90 % relative humidity (RH) at 25 °C or 80 °C at zero humidity, the optimized device retained 87 % PCE over 130 days or 95 % over 40 days, compared to the initial efficiency.     

Site‐Specific Dual Labeling of Proteins on Cysteine Residues with Chlorotetrazines

Dual‐labeled biomolecules constitute a new generation of bioconjugates with promising applications in therapy and diagnosis. Unfortunately, the development of these new families of biologics is hampered by the technical difficulties associated with their construction. In particular, the site specificity of the conjugation is critical as the number and position of payloads can have a dramatic impact on the pharmacokinetics of the bioconjugate. Herein, we introduce dichlorotetrazine as a trivalent platform for the selective double modification of proteins on cysteine residues. This strategy is applied to the dual labeling of albumin with a macrocyclic chelator for nuclear imaging and a fluorescent probe for fluorescence imaging.     

条形靶激光等离子体复合特性的理论研究

报导一个条形靶激光等离子体的计算程序JLULP1,并首次用此程序研究了条形Si靶激光等离子体的空间和时间分布特性及其与靶形状之间的关系.结果表明,条形靶产生的激光等离子体比圆柱形靶产生的激光等离子体更有利于三体复合.     

Gas‐phase doubly charged complexes of cyclic peptides with copper in +1, +2 and +3 formal oxidation states: formation,structures and electron capture dissociation

Copper complexes with a cyclic D‐His‐β‐Ala‐L‐His‐L‐Lys and all‐L‐His‐β‐Ala‐His‐Lys peptides were generated by electrospray which were doubly charged ions that had different formal oxidation states of Cu(I), Cu(II) and Cu(III) and different protonation states of the peptide ligands. Electron capture dissociation showed no substantial differences between the D‐His and L‐His complexes. All complexes underwent peptide cross‐ring cleavages upon electron capture. The modes of ring cleavage depended on the formal oxidation state of the Cu ion and peptide protonation. Density functional theory (DFT) calculations, using the B3LYP with an effective core potential at Cu and M06‐2X functionals, identified several precursor ion structures in which the Cu ion was threecoordinated to pentacoordinated by the His and Lys side‐chain groups and the peptide amide or enolimine groups. The electronic structure of the formally Cu(III) complexes pointed to an effective Cu(I) oxidation state with the other charge residing in the peptide ligand. The relative energies of isomeric complexes of the [Cu(c‐HAHK + H)]²⁺ and [Cu(c‐HAHK ? H)]²⁺ type with closed electronic shells followed similar orders when treated by the B3LYP and M06‐2X functionals. Large differences between relative energies calculated by these methods were obtained for open‐shell complexes of the [Cu(c‐HAHK)]²⁺ type. Charge reduction resulted in lowering the coordination numbers for some Cu complexes that depended on the singlet or triplet spin state being formed. For [Cu(c‐HAHK ? H)]²⁺ complexes, solution H/D exchange involved only the N–H protons, resulting in the exchange of up to seven protons, as established by ultra‐high mass resolution measurements. Contrasting the experiments, DFT calculations found the lowest energy structures for the gas‐phase ions that were deprotonated at the peptide C_α positions. Copyright © 2012 John Wiley & Sons, Ltd.     

Nanodosimetric kinetic model incorporating localized and delocalized recombination: Application to the prediction of the electron dose response of the peak 5a/5 ratio in the glow curve of LiF:Mg,Ti (TLD-100)

A kinetic model combining both localized and delocalized recombination is described which is based on different filling rates as a function of irradiation electron energy of a spatially correlated trapping center/luminescent center (TC/LC) complex. Following irradiation and thermal de-trapping the locally trapped electron-hole configuration is assumed to give rise to peak 5a and the e-only configuration to peak 5 in the glow curve of LiF:Mg,Ti (TLD-100). The model is capable of simulating the linear/supralinear dose response of composite peak 5, the dependence of the supralinearity on photon energy and the ratio of the intensities of peak 5a to peak 5 as a function of dose. However, this is achieved only by invoking the presence of band-tail states which allow thermally induced hopping leading to semi-localized recombination in the recombination mechanism of the e-only configuration.     

Nature of the impurity bands of the edge luminescence of highly doped compensated ZnSe:N

A modification of the model of potential fluctuations is suggested to explain the experimentally observed dependences of the form and position of the maxima in the impurity luminescence spectra of ZnSe specimens, highly doped with an acceptor nitrogen impurity, on the degree of doping, excitation level, temperature, and decay time. In this model, analysis of the recombination of donor-acceptor pairs is replaced by consideration of transitions from localized and delocalized states of the donor impurity band and density tail of the conduction-band states, which appear in strong doping because of the overlapping of wave functions of the donor states, to the acceptor levels. The influence of the parameter of the electron-phonon interaction on the spectrum shape is considered. The model allows one to offer a consistent explanation at the qualitative level for the features observed experimentally. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 86–90, January–February, 2000.     

Two‐photon absorption induced anti‐Stokes emission in single InGaN/GAN quantum‐dot‐like objects

We observed crossed transitions and anti‐Stokes emissions in single quantum‐dot‐like objects embedded in the active layer of InGaN/GaN quantum disks by two‐photon absorption techniques. We proposed a phenomenological model based on the interplay between Auger effect and crossed transitions to explain the origin of anti‐Stokes emissions and the preferential excitation of 0D objects at the expense of their surroundings. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

钙钛矿光伏电池的非辐射复合损耗及调控策略

基于金属卤化物的钙钛矿光伏电池(PSCs)具有较大的光吸收系数、长的载流子扩散距离以及较低的制备成本等优势,在过去十几年来得到了研究者的广泛关注,目前最高光电转换效率(PCE)已经达到25.5%。然而,由于载流子运输过程中存在各类非辐射复合损耗,器件的PCE仍然低于肖克利-奎伊瑟理论极限。本文围绕PSCs的结构与工作原理,着重综述了器件工作过程中常见的非辐射复合方式,具体包括缺陷辅助复合、界面诱导复合、俄歇复合和带尾复合等,这些复合方式作为影响器件效率与工作稳定性的重要因素,受到研究者的广泛关注。结合最新的研究进展,从减小钙钛矿晶体缺陷、钝化晶界缺陷、钝化表面缺陷、优化能级结构等四个方面总结概括了降低非辐射复合的常用措施和策略。最后,对PSCs的非辐射复合调控前景进行了展望。     

Transmission electron microscopy study of defects in AlN crystals with rough and smooth surface grains

Defects present in (0 0 0 1) textured polycrystalline AlN grown by the sublimation–recombination method were analyzed using transmission electron microscopy (TEM) methods. Grains in the polycrystalline boule had either a smooth or a rough surface. The rough surface grains had mainly edge dislocations, whereas the smooth surface grains had some sub-grain boundaries and were mostly free of dislocations. Dislocations at the grain boundaries were pinned and could not be annihilated.     

Excited‐State Prototropic Equilibrium Dynamics of 6‐Hydroxyquinoline Encapsulated in Microporous Catalytic Faujasite Zeolites

The excited‐state proton transfer and geminate recombination of 6‐hydroxyquinoline (6HQ) encaged in catalytic Na⁺‐exchanged faujasite zeolites X (NaX) and Y (NaY) have been explored by measuring steady‐state and picosecond time‐resolved spectra. The pathways and rate constants of proton transfer of excited 6HQ are determined by the microscopic environment of zeolitic hosts surrounding the guest molecules. The excited‐state proton transfer of a 6HQ molecule encapsulated in a zeolitic nanocavity is initiated by deprotonation of the enolic group to form an anionic intermediate and completed by subsequent protonation of the imino group to form a zwitterionic tautomer. Geminate recombination occurs to compete with proton transfer at each tautomerization step of excited‐state 6HQ because of the confined environment of dehydrated zeolitic supercages. Consequently, excited‐state equilibria among three prototropic species of 6HQ are established in microporous catalytic faujasite zeolites. Kinetic differences in NaX and NaY are attributed to dissimilarities in acidity/basicity.