Multilayered 2D Cesium-Based Hybrid Perovskite with Strong Polarization Sensitivity: Dimensional Reduction of CsPbBr3

3D perovskite CsPbBr₃ has recently taken a blooming position for optoelectronic applications. However, due to the lack of natural anisotropy of optical attributes, it is a great challenge to fulfil polarization-sensitive photodetection. Here, for the first time, we exploited dimensionality reduction of CsPbBr₃ to tailor a 2D-multilayered hybrid perovskite, (TRA)₂CsPb₂Br₇ ( 1 , in which TRA is (carboxy)cyclohexylmethylammonium), serving as a potential polarized-light detecting candidate. Its unique quantum-confined 2D structure results in intrinsic anisotropy of electrical conductivity, optical absorbance, and polarization-dependent responses. Particularly, it exhibits remarkable dichroism with the photocurrent ratio (I_pc/I_pa) of ≈2.1, being much higher than that of the isotropic CsPbBr₃ crystal and reported CH₃NH₃PbI₃ nanowire (≈1.3), which reveals its great potentials for polarization-sensitive photodetection. Further, crystal-based detectors of 1 show fascinating responses to the polarized light, including high detectivity (>10¹⁰ Jones), fast responding time (≈300 μs), and sizeable on/off current ratios (>10⁴). To our best knowledge, this is the first study on 2D Cs-based hybrid perovskite exhibiting strong polarization-sensitivity. The work highlights an effective pathway to explore new polarization sensitive candidates for hybrid perovskites and promotes their future electronic applications.     

Amino-Acid-Induced Circular Polarized Luminescence in One-Dimensional Manganese(II) Halide Hybrid

Circular polarized luminescence (CPL)-active materials attract great attentions owing to their widely applications in 3D optical displays and encrypted transmission. Inspired by the strategies adopted in perovskite based CPL materials, herein, CPL-active hybrids (D)- and (L)-(tert-butyl prolinate)MnCl₃ were successfully prepared by assembling chiral D/L tert-butyl prolinate with manganese (II) chloride. Single crystal structures show the as-formed hybrids possess one-dimensional (1D) structure containing linear chains of face-sharing MnCl₆ octahedral surrounded by prolinate cations. The 1D Mn(II) hybrids display strong red emission peaked at 646 nm with PLQY of 67.1 % and 57.2 % for d -type and l -type, respectively, representing the highest PLQY for 1D Mn^II hybrids. Interestingly, the 1D Mn(II) hybrids exhibit prominent circular dichroism (CD) signals and remarkable CPL activity with the dissymmetry factor g of 6.1*10⁻³ and −6.3*10⁻³ from 550 to 800 nm for (D)- and (L)-(tert-butyl prolinate)MnCl₃, respectively, owing to the existence of chiral cations. It is worthy noted the obtained g represents the highest value for non-lead organic–inorganic hybrids.     

Chiral Dinuclear EuIII,TbIII, and YIII Complexes Supported by P-Stereogenic Linear Tetraphosphine Tetraoxide

A P-stereogenic linear tetraphosphine tetraoxide, (R,R)- or (S,S)-dpmppm(=O)₄, was synthesized to prepare C₂ dinuclear M(hfa)₃ complexes (M=Eu, Tb, Y) as the first example of lanthanide(III) complexes with P-chiral multidentate phosphine oxides. The mononuclear M(hfa)₃ complexes (M=Eu, Y) with a P-chiral diphosphine dioxide, tpdpb(=O)₂, were also prepared, and comparison of their photophysical properties for the Eu^III complexes revealed that significant chiral induction from the P-chiral centers arises on the achiral M(hfa)₃ units through intramolecular π-π stacking constraint in the dinuclear system.     

Nanosized Carbon Macrocycles Based on a Planar Chiral Pseudo Meta-[2.2]Paracyclophane

Structural designs combining cycloparaphenylenes (CPPs) backbone with planar chiral [2.2]paracyclophane ([2.2]PCP) lead to optical-active chiral macrocycles with intriguing properties. X-ray crystal analysis revealed aesthetic necklace-shaped structures and size-dependent packages with long-range channels. The macrocycles exhibit unique photophysical properties with high fluorescence quantum yield of up to 82 %, and the fluorescent color varies with ring size. In addition, size-dependent chiroptical properties with moderately large CPL dissymmetry factor of 10⁻³ and CPL brightness in the range of 30–40 M⁻¹ cm⁻¹ were observed.     

Control of Axial Chirality by Planar Chirality Based on Optically Active [2.2]Paracyclophane

Optically active X-shaped molecules based on the planar chiral [2.2]paracyclophane building block were prepared, in which di(methoxy)terphenyl units were stacked on the central benzene rings. At 25 °C, anisolyl rings freely rotate in solution, while in the crystal form, they are fixed by intramolecular CH–π interactions, thereby leading to the expression of the axial chirality, i.e., propeller chirality was exhibited by the planar chiral [2.2]paracyclophane moiety. The X-shaped molecule exhibited good circularly polarized luminescence (CPL) profiles with moderate Φ_PL and a large g_lum value in the order of 10⁻³ at 25 °C, in solution. In contrast, at −120 °C, dual CPL emission with opposite signs was observed. According to the theoretical studies, the rotary motion of the anisolyl units is suppressed in the excited states, and so emission from two isomers could be observed. These results demonstrate that the axial chirality was controlled by the planar chirality, leading ultimately to propeller chirality.     

Comparison of Various Films Used in Biophysical Investigations as Anisotropic Matrices

Polarized spectra of biological molecules oriented in artificial systems can give useful information of structural and spectroscopical properties of these molecules^1,2. Such investigations have been carried out recently for several biological systems: chlorophylls^{3, 4, 5, 6, 7}, carotenoids⁸, biliproteins^{9, 10}, bacterial reaction centers^{11, 12}, bacteriochlorophylls¹³ etc.     

手性无机纳米材料圆偏振发光的研究进展

手性无机纳米材料因为具有优异的光物理特性及广泛的应用价值而备受关注。通过采用手性配体对无机纳米材料的表面进行修饰或将无机纳米材料与手性模板进行组装获得的手性结构,可以与光子强烈作用引起偏振态的改变,产生圆偏振光(circularly polarized light, CPL)。从产生机理来讲,CPL主要包括圆偏振荧光和圆偏振散射,在一些情况下这两个机理是共存的。本文总结了硫族半导体纳米材料、金属纳米团簇、钙钛矿、镧系配合物及其他复合纳米材料中CPL的研究进展。此外,还讨论了不同的手性无机纳米材料中CPL的主要来源。本综述得出的结论有望在分子水平上实现对CPL活性材料的各向异性因子进行调控,促进其在量子计算、光学数据存储、信息加密、3D显示器和光学传感等多个领域的发展。     

超分子组装体激发态手性的响应性

圆偏振发光主要是指手性发光体系激发态的性质。由于其在信息加密、高分辨3D显示和智能传感器等领域的潜在应用而备受关注。圆偏振光除了可以通过物理方法获得,即使用线偏振片和四分之一波片的组合,还可以直接从具有光致发光或电致发光性质的手性材料中获得。目前研究者们已经开发了多种圆偏振发光材料,主要包括手性有机分子、手性金属配合物等小分子发光体系以及手性超分子组装体等复合体系。通过将手性组分与响应性功能基团结合而构筑的响应性自组装发光体系对实现智能圆偏振发光材料的发展起着重要作用。在这篇文章里,我们对手性超分子自组装发光体系对各种外界刺激的响应性能进行了总结和归纳,如光照、pH值、溶剂、温度、金属离子等。本综述通过对各种外部刺激对手性组装体激发态性能影响的总结和讨论,旨在进一步推动智能圆偏振发光材料在多学科领域的应用。     

Triplet pairing states with equal spins in ferromagnet/superconductor heterojunctions for noncollinear magnetizations

Four-component Bogoliubov-de Gennes equations are applied to study tunneling conductance spectra of ferromagnet/ferromagnet/d-wave superconductor (F₁/F₂/d-wave S) tunnel junctions and to find out signs of spin-triplet pairing correlations induced in the proximity structure. The pairing correlations with equal spins arises from the novel Andreev reflection (AR), which requires at least three factors: the usual AR at the F₂/S interface, spin flip in the F₂ layer, and superconducting coherence kept up in the F₂ layer. Effects of angle α between magnetizations of the two F layers, polarizations of the F₁ and F₂ layers, the thickness of the F₂ layer, and the orientation of the d-wave S crystal on the tunneling conductance are investigated. A conversion from a zero-bias conductance dip at α = 0 to a zero-bias conductance peak at a certain value of α can be seen as a sign of generated spin-triplet correlations.