Two-dimensional(2D)fully compensated collinear magnetic materials ofer signifcant advantages for spintronic applications,including robustness against magnetic feld perturbations,no stray felds,and ultrafast dynamics.A...Two-dimensional(2D)fully compensated collinear magnetic materials ofer signifcant advantages for spintronic applications,including robustness against magnetic feld perturbations,no stray felds,and ultrafast dynamics.Among these materials,fully compensated ferrimagnets are particularly promising due to their unique characteristics such as the magneto-optical efect,completely spin-polarized currents,and the anomalous Hall efect.We performed a structural search on 2D unconventional stoichiometric Cr-I crystals using a global optimization algorithm.The most stable CrI-P21/m monolayer is a fully compensated ferrimagnetic semiconductor with a band gap of 1.57 eV and a high magnetic transition temperature of 592 K.The spontaneous spin splitting in CrI-P21/m originates from the inequivalent local coordination environments of Cr^(1)and Cr^(2)ions,yielding a mismatch in their 3d orbitals splitting.Notably,carrier doping at a concentration of 0.01 electrons or holes per atom enables reversible spin polarization,generating a fully spin-polarized current in CrI-P21/m.This performance makes it a highly promising candidate for spintronic devices.Our fndings not only provide a structural paradigm for discovering fully compensated ferrimagnets but also open a new avenue for designing zero-moment magnetic materials with intrinsic spin splitting.展开更多
Despite the great leap forward perovskite solar cells(PSCs)have achieved in power conversion efficiency,the device instability remains one of the major problems plaguing its commercialization.Dopant-free hole transpor...Despite the great leap forward perovskite solar cells(PSCs)have achieved in power conversion efficiency,the device instability remains one of the major problems plaguing its commercialization.Dopant-free hole transport material(HTM)has been widely studied as an important strategy to improve the stability of PSCs due to its avoidance of moisture-sensitive dopants and cumbersome doping process.In this work,a series of dopant-free HTMs L1F,L2F and L3F based on D-A-π-A-D configuration were synthesized through two steps of reaction.L3F presents a high glass transition temperature of 1800C and thermal decomposition temperature of 4480C.Notably,electron paramagnetic resonance signals of L1F,L2F and L3F powders indicate the open-shell quinoidal diradical resonance structure in their aggregation state due to aggregation-induced radical effect.All these HTMs present higher hole mobility than dopant-free Spiro-OMeTAD,and the dopant-free L3F-based PSC device achieves the highest power conversion efficiency of 17.6%among them.In addition,due to the high hydrophobic properties of L1F,L2F and L3F,the perovskite films spin-coated with these HTMs exhibit higher humidity stability than doped SpiroOMeTAD.These results demonstrate a promising design strategy for high glass transition temperature dopant-free hole transport material.The open-shell quinoid-radical organic semiconductors are not rational candidates for dopant-free HTMs for PSC devices.展开更多
The structural stability of Zn2GeO4 was investigated by in-situ synchrotron radiation angle dispersive x-ray diffraction. The pressure-induced amorphization is observed up to 10 GPa at room temperature. The high-press...The structural stability of Zn2GeO4 was investigated by in-situ synchrotron radiation angle dispersive x-ray diffraction. The pressure-induced amorphization is observed up to 10 GPa at room temperature. The high-pressure and hightemperature sintering experiments and the Raman spectrum measurement firstly were performed to suggest that the amorphization is caused by insufficient thermal energy and tilting Zn–O–Ge and Ge–O–Ge bond angles with increasing pressure,respectively. The calculated bulk modulus of Zn2GeO4 is 117.8 GPa from the pressure-volume data. In general, insights into the mechanical behavior and structure evolution of Zn2GeO4 will shed light on the micro-mechanism of the materials variation under high pressure and high temperature.展开更多
基金supported by the Natural Science Foundation of Wenzhou Institute,University of Chinese Academy of Sciences(UCAS)(Grant No.WIUCASQD2023004)the National Natural Science Foundation of China(Grant Nos.12304006,12404265,and 12435001)+2 种基金the Natural Science Foundation of Shanghai,China(Grant No.23JC1401400)the Natural Science Foundation of Wenzhou(Grant No.L2023005)the Fundamental Research Funds for the Central Universities of East China University of Science and Technology。
文摘Two-dimensional(2D)fully compensated collinear magnetic materials ofer signifcant advantages for spintronic applications,including robustness against magnetic feld perturbations,no stray felds,and ultrafast dynamics.Among these materials,fully compensated ferrimagnets are particularly promising due to their unique characteristics such as the magneto-optical efect,completely spin-polarized currents,and the anomalous Hall efect.We performed a structural search on 2D unconventional stoichiometric Cr-I crystals using a global optimization algorithm.The most stable CrI-P21/m monolayer is a fully compensated ferrimagnetic semiconductor with a band gap of 1.57 eV and a high magnetic transition temperature of 592 K.The spontaneous spin splitting in CrI-P21/m originates from the inequivalent local coordination environments of Cr^(1)and Cr^(2)ions,yielding a mismatch in their 3d orbitals splitting.Notably,carrier doping at a concentration of 0.01 electrons or holes per atom enables reversible spin polarization,generating a fully spin-polarized current in CrI-P21/m.This performance makes it a highly promising candidate for spintronic devices.Our fndings not only provide a structural paradigm for discovering fully compensated ferrimagnets but also open a new avenue for designing zero-moment magnetic materials with intrinsic spin splitting.
基金financially supported by the Natural Science Foundation of China(Nos.51973063 and 22375065)。
文摘Despite the great leap forward perovskite solar cells(PSCs)have achieved in power conversion efficiency,the device instability remains one of the major problems plaguing its commercialization.Dopant-free hole transport material(HTM)has been widely studied as an important strategy to improve the stability of PSCs due to its avoidance of moisture-sensitive dopants and cumbersome doping process.In this work,a series of dopant-free HTMs L1F,L2F and L3F based on D-A-π-A-D configuration were synthesized through two steps of reaction.L3F presents a high glass transition temperature of 1800C and thermal decomposition temperature of 4480C.Notably,electron paramagnetic resonance signals of L1F,L2F and L3F powders indicate the open-shell quinoidal diradical resonance structure in their aggregation state due to aggregation-induced radical effect.All these HTMs present higher hole mobility than dopant-free Spiro-OMeTAD,and the dopant-free L3F-based PSC device achieves the highest power conversion efficiency of 17.6%among them.In addition,due to the high hydrophobic properties of L1F,L2F and L3F,the perovskite films spin-coated with these HTMs exhibit higher humidity stability than doped SpiroOMeTAD.These results demonstrate a promising design strategy for high glass transition temperature dopant-free hole transport material.The open-shell quinoid-radical organic semiconductors are not rational candidates for dopant-free HTMs for PSC devices.
基金Project supported by the Joint Fund of the National Natural Science Foundation of China and Chinese Academy of Sciences(Grant No.U1332104)
文摘The structural stability of Zn2GeO4 was investigated by in-situ synchrotron radiation angle dispersive x-ray diffraction. The pressure-induced amorphization is observed up to 10 GPa at room temperature. The high-pressure and hightemperature sintering experiments and the Raman spectrum measurement firstly were performed to suggest that the amorphization is caused by insufficient thermal energy and tilting Zn–O–Ge and Ge–O–Ge bond angles with increasing pressure,respectively. The calculated bulk modulus of Zn2GeO4 is 117.8 GPa from the pressure-volume data. In general, insights into the mechanical behavior and structure evolution of Zn2GeO4 will shed light on the micro-mechanism of the materials variation under high pressure and high temperature.
