Trinuclear Cage-Like Zn(II) Macrocyclic Complexes: Enantiomeric Recognition and Gas Adsorption Properties.

Three zinc(II) ions in combination with two units of enantiopure [3+3] triphenolic Schiff-base macrocycles 1, 2, 3, or 4 form cage-like chiral complexes. The formation of these complexes is accompanied by the enantioselective self-recognition of chiral macrocyclic units. The X-ray crystal structures of these trinuclear complexes show hollow metal-organic molecules. In some crystal forms, these barrel-shaped complexes are arranged in a window-to-window fashion, which results in the formation of 1D channels and a combination of both intrinsic and extrinsic porosity. The microporous nature of the [Zn3 12 ] complex is reflected in its N2 , Ar, H2 , and CO2 adsorption properties. The N2 and Ar adsorption isotherms show pressure-gating behavior, which is without precedent for any noncovalent porous material. A comparison of the structures of the [Zn3 12 ] and [Zn3 32 ] complexes with that of the free macrocycle H3 1 reveals a striking structural similarity. In H3 1, two macrocyclic units are stitched together by hydrogen bonds to form a cage very similar to that formed by two macrocyclic units stitched together by Zn(II) ions. This structural similarity is manifested also by the gas adsorption properties of the free H3 1 macrocycle. Recrystallization of [Zn3 12 ] in the presence of racemic 2-butanol resulted in the enantioselective binding of (S)-2-butanol inside the cage through the coordination to one of the Zn(II) ions.This work was supported by the NCN (NarodoweCentrumNauki, Poland) (grant 2011/03/B/ST5/01060).D.P.and J.L.thank the FNP Program“Mistrz” for financial support, and D.F.-J. thanks the Royal Society for funding through a University Research Fellowship.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/chem.20150347

Trinuclear Cage-Like ZnII Macrocyclic Complexes: Enantiomeric Recognition and Gas Adsorption Properties

Three zinc(II) ions in combination with two units of enantiopure 3+3 triphenolic Schiff base macrocycles 1, 2, 3 or 4 form cage-like chiral complexes. The formation of these complexes is accompanied by the enantioselective self-recognition of chiral macrocyclic units. The X-ray crystal structures of these trinuclear complexes show hollow metal-organic molecules. In some crystal forms, these barrel-shaped complexes are arranged in a window-to-window fashion which results in formation of 1-D channels and combination of intrinsic porosity with extrinsic porosity. The microporous nature of the [Zn312] complex is reflected in its N2, Ar, H2 and CO2 adsorption properties. The N2 and Ar adsorption isotherms showed pressure gating behaviour which is without precedent for any noncovalent porous material. The comparison of the structures of the [Zn312] and [Zn332] complexes with that of the free macrocycle H31 reveals a striking structural similarity. In the latter compound two macrocyclic units stitched together by hydrogen bonds form a cage very similar to that formed by two macrocyclic units stitched together by Zn(II) ions. This structural similarity is manifested also by the gas adsorption properties of the free H31 macrocycle. Recrystallization of [Zn312] in the presence of racemic 2-butanol results in enantioselective binding of the (S)-2-butanol inside the cage via coordination to one of Zn(II) ions.This work was supported by the NCN (NarodoweCentrumNauki, Poland) (grant 2011/03/B/ST5/01060).D.P.and J.L.thank the FNP Program“Mistrz” for financial support, and D.F.-J. thanks the Royal Society for funding through a University Research Fellowship.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/chem.20150347

Speciation of Lanthanide Metal Ion Dopants in Microcrystalline All-Inorganic Halide Perovskite CsPbCl3

Lanthanides are versatile modulators of optoelectronic properties owing to their narrow optical emission spectra across the visible and near-infrared range. Their use in metal halide perovskites (MHPs) has recently gained prominence, although their fate in these materials has not yet been established at the atomic level. We use cesium-133 solid-state NMR to establish the speciation of all nonradioactive lanthanide ions (La3+, Ce3+, Pr3+, Nd3+, Sm3+, Sm2+, Eu3+, Eu2+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+) in microcrystalline CsPbCl3. Our results show that all lanthanides incorporate into the perovskite structure of CsPbCl3 regardless of their oxidation state (+2, +3)

Speciation of Lanthanide Metal Ion Dopants in Microcrystalline All-Inorganic Halide Perovskite CsPbCl3

Lanthanides are versatile modulators of optoelectronic properties owing to their narrow optical emission spectra across the visible and near-infrared range. Their use in metal halide perovskites (MHPs) has recently gained prominence, although their fate in these materials has not yet been established at the atomic level. We use cesium-133 solid-state NMR to establish the speciation of all nonradioactive lanthanide ions (La3+, Ce3+, Pr3+, Nd3+, Sm3+, Sm2+, Eu3+, Eu2+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+) in microcrystalline CsPbCl3. Our results show that all lanthanides incorporate into the perovskite structure of CsPbCl3 regardless of their oxidation state (+2, +3).</p

Local Structure and Dynamics in Methylammonium, Formamidinium, and Cesium Tin(II) Mixed-Halide Perovskites from 119Sn Solid-State NMR.

Organic-inorganic tin(II) halide perovskites have emerged as promising alternatives to lead halide perovskites in optoelectronic applications. While they suffer from considerably poorer performance and stability in comparison to their lead analogues, their performance improvements have so far largely been driven by trial and error efforts due to a critical lack of methods to probe their atomic-level microstructure. Here, we identify the challenges and devise a 119Sn solid-state NMR protocol for the determination of the local structure of mixed-cation and mixed-halide tin(II) halide perovskites as well as their degradation products and related phases. We establish that the longitudinal relaxation of 119Sn can span 6 orders of magnitude in this class of compounds, which makes judicious choice of experimental NMR parameters essential for the reliable detection of various phases. We show that Cl/Br and I/Br mixed-halide perovskites form solid alloys in any ratio, while only limited mixing is possible for I/Cl compositions. We elucidate the degradation pathways of Cs-, MA-, and FA-based tin(II) halides and show that degradation leads to highly disordered, qualitatively similar products, regardless of the A-site cation and halide. We detect the presence of metallic tin among the degradation products, which we suggest could contribute to the previously reported high conductivities in tin(II) halide perovskites. 119Sn NMR chemical shifts are a sensitive probe of the halide coordination environment as well as of the A-site cation composition. Finally, we use variable-temperature multifield relaxation measurements to quantify ion dynamics in MASnBr3 and establish activation energies for motion and show that this motion leads to spontaneous halide homogenization at room temperature whenever two different pure-halide perovskites are put in physical contact

Understanding the Origin of Light Intensity and Temperature Dependence of Photodetection Properties in MAPbBr3 Single Crystal-based Photoconductor

Methylammonium lead bromide (MAPbBr3), which belongs to the larger material family of lead halide perovskites (LHPs), has emerged as a promising semiconductor for the fabrication of single crystal (SC) based photodetectors (PDs). However, there is still a lack of sufficient understanding of the effect of irradiation power and applied temperature on the photodetection performance of SC based perovskite PDs. Here, we investigate the impact of different light intensities and temperatures on the photodetection properties of planar-type MAPbBr3 SC based PD with the help of transient photoresponse and impedance spectroscopy. The light intensity-dependent study revealed that the key performance parameters of PD decrease with increasing irradiation intensity due to changes in charge recombination and carrier lifetime. On the other hand, the detrimental effect of increasing temperature on the performance of PD was found to be related to the ions accumulation, increasing scattering of impurities and phonons, change in conductivity and band gap rather than the change in charge recombination. This study provides a thorough understanding of the origin of light intensity and temperature-dependent photodetection properties of SC based PD, which is crucial for the further advancement of optoelectronic devices based on LHPs.National Science Centr

Metal-Doped MAPbBr3 Single Crystal p-n Junction Photodiode for Self-Powered Photodetection

Lead halide perovskites have emerged as the next-generation materials for self-powered photodetectors enabling operation without an external power source. In this study, a planar-type photodetector based on metal-doped p-type MAPbBr3/n-type MAPbBr3 single crystal showing excellent self-powered photodetection properties is presented. The p-n junction on the MAPbBr3 single crystal is formed by controlled epitaxial growth of Ag+-doped MAPbBr3 SC (p-type) on the facet of Sb3+-doped MAPbBr3 SC (n-type). The as-integrated p-n junction device with asymmetric electrodes shows a typical photovoltaic behavior with a high open circuit voltage of 0.95 V and great sensitivity to 530 nm illumination at zero bias with a responsivity of up to 0.41 A W−1 and a specific detectivity of 6.39 × 1011 Jones, which are among the highest values reported for MAPbBr3 single crystal-based self-powered photodetectors. In addition, the rise time and fall time of this device are as fast as 14 and 10 ms, respectively. These results pave the way for the fabrication of self-powered perovskite-based p-n junction photodiode, which may find potential application in advanced photodiode and future optoelectronic devices.National Science Centr

Ionic liquid-assisted growth of high-quality methylammonium lead bromide single crystals for photodetection applications

The control of nucleation temperature and growth kinetics during inverse temperature crystallization (ITC) is critical for achieving high-quality perovskite single crystals (SCs) for various optoelectronic applications. Here, we show that the addition of a 1-butyl-3-methylimidazolium bromide (BMIB) ionic liquid to the methylammonium lead bromide (MAPbBr3) precursor solution not only reduces the nucleation temperature from 80 1C to 60 1C but also substantially improves the crystal quality and optoelectronic properties. Specifically, MAPbBr3 SCs grown in the presence of BMIB exhibit better crystallinity with reduced lattice strain, nonradiative recombination and trap density compared to the MAPbBr3 SCs grown by the conventional ITC method at 80 1C. The high quality of the BMIB-based MAPbBr3 SCs enabled us to build an efficient planar-structured photodetector with high responsivity to green light (530 nm). This study shows that the ionic liquid-assisted growth of perovskite SCs has a significant influence on the crystal properties, which is beneficial for optoelectronic SC-based devices.National Science Centr

Transient Photocurrent Response in a Perovskite Single Crystal-Based Photodetector: A Case Study on the Role of Electrode Spacing and Bias

Transient photocurrent is a widely applied characterization technique to probe the charge-carrier photogeneration and extraction dynamics in perovskite optoelectronic devices. Despite the large number of studies on the properties of perovskite single-crystals (SCs) photodetectors (PDs), the underlying mechanism that governs the spectral line shape of transient photocurrent is not fully understood. Here, methylammonium lead bromide (MAPbBr3)SC based PDs are used to study the effect of different electrode spacing and bias on the transient photocurrent response under blue and green light irradiation. The observed differences in the spectral line shape of the transient photocurrent are explained using three-step carrier transport model, which reveals the occurrence of carrier trapping and a recombination process in MAPbBr3 SC. The findings are further corroborated by intensity-dependent photocurrent and impedance spectroscopy analysis of the resulting PDs. This work provides a basic insight into the origin of the different behavior of transient photocurrent response under variable electrode distance, bias, and irradiance light, which is expected to help to further understand and optimize the performance of perovskite based PDs.National Science Centr