A Multifunctional Liquid Crystal as Hole Transport Layer Additive Enhances Efficiency and Stability of Perovskite Solar Cells

Lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) has been identified as the most used and effective p-dopant for hole transport layer (HTL) in perovskite solar cells (PSCs). However, the migration and agglomeration of Li-TFSI in HTL negatively impact PSCs performance and stability. Herein, we report an effective strategy for adding a liquid crystal organic small molecule (LQ) into Li-TFSI doped (2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′- spirobifluorene (Spiro-OMeTAD) HTL. It was found that the introduction of LQ into Spiro-OMeTAD HTL can efficiently enhance the charge carrier extraction and transportation in device, which can strongly retard the charge carrier recombination in device. Consequently, the PSCs efficiency is significantly enhanced to 24.42 % (Spiro-OMeTAD+LQ) from 21.03 % (Spiro-OMeTAD). The chemical coordination between LQ and Li-TFSI can strongly confine Li⁺ ions migration and agglomeration of Li-TFSI, thus, achieving the enhanced device stability. Only a 9 % efficiency degradation is observed for un-encapsulated device prepared with Spiro-OMeTAD and LQ after 1700 h under air environment, while the efficiency drops by 30 % for the reference device. This work provides an effective strategy for improving the efficiency and stability of PSCs, and gives some important insights for understanding intrinsic hot carriers dynamics for perovskite-based optoelectronic devices.     

Hydrocarbon Oxidation by a Porphyrin-π-Cation Radical Complex

Heme and chlorin π-cation radical oxidants are widely implicated in biological and synthetic oxidation catalysis. Little insight into the role of π-cation radicals in proton coupled electron transfer (PCET) oxidation is available. We prepared a Ni^II-porphyrin-π-cation complex ([Ni^II(P⋅⁺)]) and found it to be capable of the oxidation of a variety of simple hydrocarbon substrates. Interestingly, some of the products were hydroxylated, with ([Ni^II(P⋅⁺)]) working in concert with atmospheric O₂ to yield hydroxylated hydrocarbons. Kinetic data suggested that the porphyrin-π-cation radical species oxidised substrates through a concerted PCET mechanism, where the porphyrin-π-cation radical accepted the electron, and the proton was transferred to a free anion. Our findings highlight the potential role of π-cation radicals as hydrocarbon activators, demonstrating that porphyrin ligand non-innocence could be a readily manipulated resource for oxidation catalyst development.     

Syntheses and Properties of (Nitronyl nitroxide)-substituted Tri-phenylamine ortho-Bridged by Two Oxygen and Sulfur Atoms

A nitronyl nitroxide unit ( NN ) was linked with a triphenylamine-based condensed polycyclic skeleton DOTT to form a radical substituted donor NN - DOTT . X-ray crystal structure analysis demonstrated a flat bowl shape of the DOTT unit. EPR spectra showed the localization of electron spin on the NN unit. Chemical oxidation of the DOTT unit produced radical-substituted radical cation salts NN - DOTT ⁺ ⋅ SbF₆⁻ and NN - DOTT ⁺ ⋅ FeBr₄⁻ that are stable under ambient conditions. The magnetic behavior of NN - DOTT ⁺ ⋅ SbF₆⁻ is characterized by the strong intramolecular ferromagnetic interaction between NN and DOTT ⁺. The X-ray structural analysis of NN - DOTT ⁺ ⋅ FeBr₄⁻ shows planar structure of DOTT and 1D mixed-stack column of NN-DOTT ⁺ and FeBr₄⁻. Magnetic measurements established that NN - DOTT ⁺ ⋅ FeBr₄⁻ undergoes magnetic phase transition into a weak ferromagnet at 7 K.     

Effects of Intra-Base Pair Proton Transfer on Dissociation and Singlet Oxygenation of 9-Methyl-8-Oxoguanine−1-Methyl-Cytosine Base-Pair Radical Cations

8-Oxoguanosine is the most common oxidatively generated base damage and pairs with complementary cytidine within duplex DNA. The 8-oxoguanosine−cytidine lesion, if not recognized and removed, not only leads to G-to-T transversion mutations but renders the base pair being more vulnerable to the ionizing radiation and singlet oxygen (¹O₂) damage. Herein, reaction dynamics of a prototype Watson−Crick base pair [9MOG ⋅ 1MC]⋅⁺, consisting of 9-methyl-8-oxoguanine radical cation (9MOG⋅⁺) and 1-methylcystosine (1MC), was examined using mass spectrometry coupled with electrospray ionization. We first detected base-pair dissociation in collisions with the Xe gas, which provided insight into intra-base pair proton transfer of 9MOG⋅⁺ ⋅ 1MC [9MOG − H_N1]⋅ ⋅ [1MC+H_N3′]⁺ and subsequent non-statistical base-pair separation. We then measured the reaction of [9MOG ⋅ 1MC]⋅⁺ with ¹O₂, revealing the two most probable pathways, C5-O₂ addition and H_N7-abstraction at 9MOG. Reactions were entangled with the two forms of 9MOG radicals and base-pair structures as well as multi-configurations between open-shell radicals and ¹O₂ (that has a mixed singlet/triplet character). These were disentangled by utilizing approximately spin-projected density functional theory, coupled-cluster theory and multi-referential electronic structure modeling. The work delineated base-pair structural context effects and determined relative reactivity toward ¹O₂ as [9MOG − H]⋅>9MOG⋅⁺>[9MOG − H_N1]⋅ ⋅ [1MC+H_N3′]⁺≥9MOG⋅⁺ ⋅ 1MC.     

CsPbIBr2钙钛矿太阳能电池中通过氧气诱导Spiro-OMeTAD快速氧化

Spiro-OMeTAD是钙钛矿型太阳能电池中应用最广泛的空穴传输材料,它本身的空穴传输率很低,需要氧化之后才能满足高效率太阳能电池器件的要求.然而,Spiro-OMeTAD在空气中的氧化时间较长,同时空气中的水分会造成器件效率的下降以及器件质量不稳定等不良后果.基于此,我们通过一步法制备CsPbIBr2无机钙钛矿太阳...     

pH‐Independent Recognition of the dG ⋅ dC Base Pair in Triplex DNA: 9‐Deazaguanine N7‐(2′‐Deoxyribonucleoside) and Halogenated Derivatives Replacing Protonated dC

Triplex-forming oligonucleotides (TFOs) containing 9-deazaguanine N⁷-(2′-deoxyribonucleoside) 1a and halogenated derivatives 1b,c were synthesized employing solid-phase oligonucleotide synthesis. For that purpose, the phosphoramidite building blocks 5a – c and 8a – c were synthesized. Multiple incorporations of 1a – c in place of dC were performed within TFOs, which involved the sequence of five consecutive 1a – c ⋅ dG ⋅ dC triplets as well as of three alternating 1a – c ⋅ dG ⋅ dC and dT ⋅ dA ⋅ dT triplets. These TFOs were designed to bind in a parallel orientation to the target duplex. Triplex forming properties of these oligonucleotides containing 1a – c in the presence of Na⁺ and Mg²⁺ were studied by UV/melting-curve analysis and confirmed by circular-dichroism (CD) spectroscopy. The oligonucleotides containing 1a in the place of dC formed stable triplexes at physiological pH in the case of sequence of five consecutive 1a ⋅ dG ⋅ dC triplets as well as three alternating 1a – c ⋅ dG ⋅ dC and dT ⋅ dA ⋅ dT triplets. The replacement of 1a by 9-halogenated derivatives 1b,c further enhanced the stability of DNA triplexes. Nucleosides 1a – c also stabilized duplex DNA.     

Green Solvent Processable,Asymmetric Dopant-Free Hole Transport Layer Material for Efficient and Stable n-i-p Perovskite Solar Cells and Modules

The use of dopant-free hole transport layers (HTLs) is critical in stabilizing n-i-p perovskite solar cells (pero-SCs). However, these HTL materials are often processed with toxic solvents, which is not ideal for industrial production. Upon substituting them with green solvents, a trade-off emerges between maintaining the high crystallinity of the HTL materials and ensuring high solubility in the new solvents. In this paper, we designed a novel, linear, organic small molecule, BDT-C8-3O, by introducing an asymmetric polar oligo(ethylene glycol) side chain. This method not only overcomes the solubility limitations in green solvents but also enables stacking the conjugated main chains in two patterns, which further enhances crystallinity and hole mobility. As a result, the n-i-p pero-SCs based on chlorobenzene- or green (natural compound) solvent 3-methylcyclohexanone-processed BDT-C8-3O HTL that without any dopant delivered world-recorded power conversion efficiencies of 24.11 % (certified of 23.82 %) and 23.53 %, respectively. The devices also demonstrated remarkable operational and high-temperature stabilities, maintaining over 84 % and 79.5 % of their initial efficiency for 2000 h, respectively. Encouragingly, dopant-free BDT-C8-3O HTL exhibits significant advantages in large-area fabrication, achieving state-of-the-art PCEs exceeding 20 % for 5×5 cm² modules (active area: 15.64 cm²), even when processed using green solvents.     

Triquinoline- versus Fullerene-Based Cycloparaphenylene Ionic Complexes: Comparison of Photoinduced Charge-Shift Reactions

A triquinoline cationic moiety (TQ⋅H⁺) has recently been designed as a novel molecular unit for supramolecular chemistry. In addition to some useful features, TQ⋅H⁺ has strong electron-acceptor properties, which renders the molecular cation a unique element in nanochemistry. TQ⋅H⁺ is found to form complexes with coronene (COR) and cycloparaphenylene (CPP). In this work, we report a computational study of photoinduced electron transfer in supramolecular complexes TQ⋅H⁺-COR, TQ⋅H⁺⊂[12]CPP and (TQ⋅H⁺-COR)⊂[12]CPP. The electron-transfer rates are estimated by using the semi-classical approach. The results are compared with the data previously obtained for a structurally similar inclusion complex Li⁺@C₆₀⊂[10]CPP. In particular, we found a red solvatochromic shift for charge-shift bands in the TQ⋅H⁺-complexes unlike a blueshift showed by Li⁺@C₆₀⊂[10]CPP. This distinction is explored in terms of electronic and structural features of the systems.     

Efficient hole transport material formed by atmospheric pressure plasma functionalization of Spiro-OMeTAD

A technique to increase the conductivity of Spiro-OMeTAD using an easily scalable, non-thermal atmospheric pressure plasma jet (APPJ) is reported. An investigation of plasma functionalization demonstrated an enhancement in hole conductivity by over an order of magnitude from 9.4 × 10^?7 S cm^?1 for the pristine film to 1.15 × 10^?5 S cm^?1 for films after 5 minutes of plasma treatment. The conductivity value after plasma functionalization was comparable to that reported for 10–25% Li-TFSI-doped Spiro-OMeTAD. The increase in conductivity was correlated with a reduction in phase value observed using electrostatic force microscopy. Kelvin probe force microscopy showed an increase in work function after plasma exposure corresponding to the p-type nature of the doping. X-ray photoelectron spectroscopy revealed surface oxidation of plasma-functionalized films, as well as variation in nitrogen chemistry, with the formation of a higher binding energy quaternary nitrogen tail. Oxidation of Spiro-OMeTAD was also confirmed by the appearance of the 500 nm absorption peak using UV–vis spectroscopy. The synergistic contribution of increase in charge density in Spiro-OMeTAD due to the energetic species in the plasma jet coupled with improvement in π-π stacking of the molecules is thought to underlie the conductivity enhancement. The enhancement in positive charges can also be attributed to the formation of quinoid structures with quaternary nitrogen +N=C formed due to loss of methyl groups during plasma surface interaction. This work opens up the possibility of using an atmospheric pressure plasma jet as a simple and effective technique for doping and functionalizing Spiro-OMeTAD thin films to circumvent the detrimental issues associated with chemical dopants.     

An Exploration of the Transformation of the 8-Oxo-7,8-Dihydroguanine Radical Cation to Protonated 2-Amino-5-Hydroxy-7,9-Dihydropurine-6,8-Dione in a Base Pair

A theoretical investigation was performed to disclose the transformation mechanism of 8-oxo-7,8-dihydroguanine radical cation (8-oxoG⋅⁺) to protonated 2-amino-5-hydroxy-7,9-dihydropurine-6,8-dione (5-OH-8-oxoG) in base pair. The energy profiles for three possible pathways of the events were mapped. It is shown that direct loss of H7 from base paired 8-oxoG⋅⁺ is the only energetically favorable pathway to generate neutral radical, 8-oxoG(-H7)⋅. Further oxidation of 8-oxoG(-H7)⋅ : C to 8-oxoG(-H7)⁺ : C is exothermic. However, the 8-oxoG(-H7)⁺ : C deprotonation from all possible active sites is infeasible, indicating the inaccessible second proton loss and the lack of essential intermediate 2-amino-7,9-dihydropurine-6,8-dione (8-oxoG^OX). This makes 8-oxoG(-H7)⁺ act as the precursor of hydration leading to the generation of protonated 5-HO-8-oxoG by stepwise fashion in base pair, which would initiate the step down guanidinohydantoin (Gh) pathway. These results clearly specify the structure-dependent transformation for 8-oxoG⋅⁺ and verify the emergence of protonated 5-HO-8-oxoG in base pair.     

Effect of Proton Transfer on Electrocatalytic Water Oxidation by Manganese Phosphates

The effect of proton transfer on water oxidation has hardly been measurably established in heterogeneous electrocatalysts. Herein, two isomorphous manganese phosphates (NH₄MnPO₄ ⋅ H₂O and KMnPO₄ ⋅ H₂O) were designed to form an ideal platform to study the effect of proton transfer on water oxidation. The hydrogen-bonding network in NH₄MnPO₄ ⋅ H₂O has been proven to be solely responsible for its better activity. The differences of the proton transfer kinetics in the two materials indicate a fast proton hopping transfer process with a low activation energy in NH₄MnPO₄ ⋅ H₂O. In addition, the hydrogen-bonding network can effectively promote the proton transfer between adjacent Mn sites and further stabilize the Mn^III−OH intermediates. The faster proton transfer results in a higher proportion of zeroth-order in [H⁺] for OER. Thus, proton transfer-affected electrocatalytic water oxidation has been measurably observed to bring detailed insights into the mechanism of water oxidation.     

Novel Thienyl DPP derivatives Functionalized with Terminal Electron-Acceptor Groups: Synthesis,Optical Properties and OFET Performance

Three novel diketopyrrolopyrrole (DPP) based small molecules have been synthesized and characterized in terms of their chemical-physical, electrochemical and electrical properties. All the molecules consist of a central DPP electron acceptor core symmetrically functionalized with donor bi-thienyl moieties and flanked in the terminal positions by three different auxiliary electron-acceptor groups. This kind of molecular structure, characterized by an alternation of electron acceptor and donor groups, was purposely designed to provide a significant absorption at the longer wavelengths of the visible spectrum: when analysed as thin films, in fact, the dyes absorb well over 800 nm and exhibit a narrow optical bandgap down to 1.28 eV. A detailed DFT analysis provides useful information on the electronic structure of the dyes and on the features of the main optical transitions. Organic field-effect transistors (OFETs) have been fabricated by depositing the DPP dyes as active layers from solution: the different end-functionalization of the dyes had an effect on the charge-transport properties with two of the dyes acting as n-type semiconductors (electron mobility up to 4.4 ⋅ 10⁻² cm²/V ⋅ s) and the third one as a p-type semiconductor (hole mobility up to 2.3 ⋅ 10⁻³ cm²/V ⋅ s). Interestingly, well-balanced ambipolar transistors were achieved by blending the most performant n-type and p-type dyes with hole and electron mobility in the order of 10⁻³ cm²/V ⋅ s     

5,5′‐Hydrazinebistetrazole: An Oxidation‐stable Nitrogen‐rich Compound and Starting Material for the Synthesis of 5,5′‐Azobistetrazolates

All 5,5′‐hydrazinebistetrazoles reported in the literature are sensitive to oxidation and react with atmospheric oxygen to yield the corresponding 5,5′‐azobistetrazolates on time. Herewith, we report on the synthesis of the free acid 5,5′‐hydrazinebistetrazole (HBT) which showed to be stable on air for extended periods of time. The compound was fully characterized by analytical and spectroscopic methods and its X‐ray structure was determined by diffraction techniques. Besides, we determined its explosive properties by BAM methods and calculated its heat of formation (+414 kJ mol^?1), detonation velocity (8523 m s^?1) and detonation pressure (27.7 GPa). HBT proved to be very safe to handle (impact sensitivity: >30 J, friction sensitivity: ～108 N) and was used as a starting material for the synthesis of some already reported 5,5′‐azobistetrazolates: NH₄⁺, NH₂NH₃⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺.     

Synthesis of Oligonucleotides Containing the N6-(2-Deoxy-α,β-d-erythropentofuranosyl)-2,6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy⋅dG) Oxidative Damage Product Derived from 2′-Deoxyguanosine

N⁶-(2-Deoxy-α,β-d -erythropentofuranosyl)-2,6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy⋅dG) is a major DNA lesion produced from 2′-deoxyguanosine under oxidizing conditions. Fapy ⋅ dG is produced from a common intermediate that leads to 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-OxodGuo), and in greater quantities in cells. The impact of Fapy ⋅ dG on DNA structure and function is much less well understood than that of 8-OxodGuo. This is largely due to the significantly greater difficulty in synthesizing oligonucleotides containing Fapy ⋅ dG than 8-OxodGuo. We describe a synthetic approach for preparing oligonucleotides containing Fapy ⋅ dG that will facilitate intensive studies of this lesion in DNA. A variety of oligonucleotides as long as 30 nucleotides are synthesized. We anticipate that the chemistry described herein will provide an impetus for a wide range of studies involving Fapy ⋅ dG.     

Functional Ionic Liquid Polymer Stabilizer for High-Performance Perovskite Photovoltaics

The stability-related issues arising from the perovskite precursor inks, films, device structures and interdependence remain severely under-explored to date. Herein, we designed an ionic-liquid polymer (poly[Se-MI][BF₄]), containing functional moieties like carbonyl (C=O), selenium (Se⁺), and tetrafluoroborate (BF₄⁻) ions, to stabilize the whole device fabrication process. The C=O and Se⁺ can coordinate with lead and iodine (I⁻) ions to stabilize lead polyhalide colloids and the compositions of the perovskite precursor inks for over two months. The Se⁺ anchored on grain boundaries and the defects passivated by BF₄⁻ efficiently suppress the dissociation and migration of I⁻ in perovskite films. Benefiting from the synergistic effects of poly[Se-MI][BF₄], high efficiencies of 25.10 % and 20.85 % were exhibited by a 0.062-cm² device and 15.39-cm² module, respectively. The devices retained over 90 % of their initial efficiency under operation for 2200 h.     

Mercury‐modified Lignosulfonate‐stabilized Gold Nanoparticles as an Alternative Material for Anodic Stripping Voltammetry of Thallium

Lignosulfonate‐stabilized gold nanoparticles (AuNPs‐LS) were synthesized and subsequently used as a complexing agent for mercury ions. The obtained AuNPs‐LS/Hg²⁺ complex was characterized by means of various physicochemical techniques such as UV‐vis spectroscopy, transmission electron microscopy and cyclic voltammetry. Furthermore, the resulting complex was evaluated as an electrode modifier for the development of amperometric sensors. Upon sufficient negative potential, the bound mercury ions are reduced to form an amalgam with AuNPs‐LS. Thus, the performance of glassy carbon electrode (GCE) modified by AuNPs‐LS/Hg film was investigated as an electrochemical sensor in the determination of Tl⁺ ions in a 0.05 M EDTA at pH 4.5. The presence of the mercury containing film improves the analyte accumulation due to its ability to form a fused amalgam with thallium. The presented data indicate that the GCE/AuNPs‐LS/Hg modified electrode shows better performance toward Tl⁺ determination in comparison to bare GCE. The stripping anodic peak current of thallium was linear over its concentration range from 1.7⋅10⁻⁷ to 5.0⋅10⁻⁶ M. The detection limit (3σ) was estimated to be 1.4⋅10⁻⁷ M. The proposed method was successfully applied for the determination of thallium ions in real samples of soil derived from the area of the copper smelter near Głogów (Poland).     

Cover Feature: OH Radical-Induced Oxidation in Nucleosides and Nucleotides Unraveled by Tandem Mass Spectrometry and Infrared Multiple Photon Dissociation Spectroscopy (ChemPhysChem 23/2023)

OH⋅-induced oxidation products of DNA nucleosides and nucleotides have been structurally characterized by collision-induced dissociation tandem mass spectrometry (CID-MS²) and Infrared Multiple Photon Dissociation (IRMPD) spectroscopy. CID-MS² results have shown that the addition of one oxygen atom occurs on the nucleobase moiety. The gas-phase geometries of +16 mass increment products of 2’-deoxyadenosine (dA(O)H⁺), 2’-deoxyadenosine 5’-monophosphate (dAMP(O)H⁺), 2’-deoxycytidine (dC(O)H⁺), and 2’-deoxycytidine 5’-monophosphate (dCMP(O)H⁺) are extensively investigated by IRMPD spectroscopy and quantum-chemical calculations. We show that a carbonyl group is formed at the C8 position after oxidation of 2’-deoxyadenosine and its monophosphate derivative. For 2’-deoxycytidine and its monophosphate derivative, the oxygen atom is added to the C5 position to form a C−OH group. IRMPD spectroscopy has been employed for the first time to provide direct structural information on oxidative lesions in DNA model systems.     

A Domino Fusion of an Organic Ligand Depended on Metal-Induced and Oxygen Insertion,Unraveled by Crystallography,Mass Spectrometry,and DFT Calculations

Herein, the reaction of (1-methyl-1 H-benzo[d]imidazol-2-yl)methanamine ( L1 ) with Co(H₂O)₆Cl₂, in CH₃CN at 120 °C, leading to the 2,3,5,6-tetrakis(1-methyl-1 H-benzo[d]imidazol-2-yl)pyrazine ( 3 ), isolated as a dimeric cluster {[Co^II₂( 3 )Cl₄] ⋅ 2 CH₃CN} ( 2 ), is reported. When O₂ and H₂O are present, (1-methyl-1 H-benzo[d]imidazole-2-carbonyl)amide (H L1′ ) is first formed and crystallized as [Co^III( L1 )₂( L1′ )]Cl₂ ⋅ 2 H₂O ( 4 ) before fusion of H L1′ with L1 , giving 1-methyl-N-(1-methyl-1 H-benzo[d]imidazol-2-carbonyl)-1 H-benzo[d]imidazol-2-carboxamide (H L2′′ ) forming a one-dimensional (1D) chain of [Co^II₃( L2′′ )₂Cl₄]_n ( 5 ). The combination of crystallography and mass spectrometry (ESI-MS) of isolated crystals and the solutions taken from the reaction as a function time reveal seven intermediate steps leading to 2 , but six steps for 5 , for which a different sequence takes place. Control and isotope labeling experiments confirm the two carbonyl oxygen atoms in 5 originate from both air and water. The dependence on the metals, compared with FeCl₃ ⋅ 6 H₂O leading to a stable triheteroarylmethyl radical, is quite astounding, which could be attributed to the different oxidation states of the metals and coordination modes confirmed by DFT calculations. This metal and valence dependent process is a very useful way for selectively obtaining these large molecules, which are unachievable by common organic synthesis.     

Halogen versus Hydrogen Bonding in Binary Cocrystals: Novel Conformation a Coformer with [2+2] Photoreactivity of Criss-Crossed C=C Bonds

A series of cocrystals involving the hydrogen- and halogen-bond donor coformers catechol ( cat ) and 1,2-diiodotetrafluorobenzene ( 1,2-di-I-tFb ), respectively, is reported. Each coformer forms a cocrystal with each of the three symmetric bipyridines trans-1,2-bis(n-pyridyl)ethylene ( n , n′ -bpe , where: n=n′=2, 3, 4). Four novel cocrystals ( cat ) ⋅ ( 3,3′-bpe ), 2( 1,2-di-I-tFb ) ⋅ ( 2,2′-bpe ), 2( 1,2-di-I-tFb ) ⋅ ( 3,3′-bpe ), and ( 1,2-di-I-tFb ) ⋅ ( 4,4′-bpe ) comprise components that assemble by either O−H⋅⋅⋅N hydrogen bonds ( cat ) or N⋅⋅⋅I halogen bonds ( 1,2-di-I-tFb ). In ( cat ) ⋅ ( 3,3′-bpe ), cat acts as a template to support an intermolecular [2+2] photocycloaddition of 3,3′-bpe . The reactivity occurs via a one-dimensional (1D) hydrogen-bonded tape with stacked and criss-crossed olefins that react stereoselectively and quantitatively to form rctt-tetrakis(3-pyridyl)cyclobutane ( 3,3′-tpcb ). The reactivity of the criss-crossed olefins is facilitated by a hitherto not reported cis-gauche conformation adopted by cat . The stereochemistry of 3,3′-tpcb is confirmed in the cocrystal 2( cat ) ⋅ ( 3,3′-tpcb ).     

Ternary Hybrid Perovskite Solid Solution Single Crystals: Growth,Composition Determination and Phase Stability in Highly Moist Atmosphere

Ternary hybrid perovskite solid solutions have shown superior optoelectronic properties and better stability than their ABX₃ simple perovskite counterparts under ambient conditions. However, crystal growth and identification of the accurate composition of these complex crystalline compounds remain challenging, and their stability under extreme conditions such as in highly moist atmosphere is unknown. Herein, large-size (up to 2 cm) single crystals of ternary perovskite 0.80FAPbI₃ ⋅ x′FAPbBr₃ ⋅ y′CsPbI₃ (x′+y′=0.20) are grown. An elemental analysis method based on wavelength dispersive X-ray fluorescence is proposed to determine their accurate compositions. Among these single crystals, the composition with y′=0.12 shows the best moisture stability at 90 % relative humidity for 15 days. Other components with richer or poorer Cs⁺ ions undergo different phase segregation behaviours. The performance and stability of photodetectors based on these single crystals are tested. This work offers a deeper insight into phase stability of ternary hybrid perovskite solid solution crystals in highly moist atmosphere.