Perovskite solar cells (PSCs) employing formamidinium lead iodide (FAPbI_(3)) have shown high efficiency.However,operational stability has been issued due to phase instability of α phase FAPbI_(3) at ambient temperat...Perovskite solar cells (PSCs) employing formamidinium lead iodide (FAPbI_(3)) have shown high efficiency.However,operational stability has been issued due to phase instability of α phase FAPbI_(3) at ambient temperature.Excess precursors in the perovskite precursor solution has been proposed to improve not only power conversion efficiency (PCE) but also device stability.Nevertheless,there is a controversial issue on the beneficial effect on PCE and/or stability between excess FAI and excess PbI_(2).We report here extended X-ray absorption fine structure (EXAFS) of FAPbI_(3) to study local structural change and explain the effect of excess precursors on photovoltaic performance and stability.Perovskite films prepared from the precursor solution with excess PbI_(2)shows better stability than those from the one with excess FAI,despite similar PCE.A rapid phase transition from α phase to non-perovskite δ phase is observed from the perovskite film formed by excess FAI.Furthermore,the (Pb-I) bond distance evaluated by the Pb L_(III)-edge EXAFS study is increased by excess FAI,which is responsible for the phase transition and poor device stability.This work can provide important insight into local structure-stability relation in the FAPbI_(3)-based PSCs.展开更多
Effect of structure parameter n and its coupling with the connection mode among RuO6 octahedra of Srn＋1RUnO3n＋1 （n = 1, 2, ∞） are investigated. The gradually enhanced rotation and tilting effect with increasing n...Effect of structure parameter n and its coupling with the connection mode among RuO6 octahedra of Srn＋1RUnO3n＋1 （n = 1, 2, ∞） are investigated. The gradually enhanced rotation and tilting effect with increasing n are observed in Srn＋1RUnO3n＋1. Besides, the chemical valence of Ru is not changed, while the one of Sr gradually varies with increasing n, which highlights the great contribution of connection mode to the chemical environment. Our results show a strong n dependence on the connection mode between octahedra in Srn＋1RUnO3n＋1 （n = 1, 2, ∞）.展开更多
Macrocycle compounds have great importance in host-guest chemistry and moleculeidentifications. 4-acetyl-bispyrazolones are a new type of polydentate ligands. Whenthey react with diamine compounds, new compounds or co...Macrocycle compounds have great importance in host-guest chemistry and moleculeidentifications. 4-acetyl-bispyrazolones are a new type of polydentate ligands. Whenthey react with diamine compounds, new compounds or complexes containing C=O andC=N groups can be obtained. These compounds can be used to study the relationship ofcoordination structure and its properties, energy transferring processes between metal展开更多
The effects of organic ethers such as diethyl ether, ethylene glycol diethyl ether and diethyl glycol diethyl ether on the structure of double metal cyanide complex catalyst and the structural changes of such catalyst...The effects of organic ethers such as diethyl ether, ethylene glycol diethyl ether and diethyl glycol diethyl ether on the structure of double metal cyanide complex catalyst and the structural changes of such catalyst in the process of propylene oxide polymerization were investigated by EXAFS. The results show that Co in all DMC catalysts is still coordinated by six cyanogens, while Zn is coordinated by O atom in organic complex. The more numerous the number of the ether bond, the higher the coordination numbers of O to Zn ion, the more active the catalyst we make. Five or six O atoms coordinated Zn ion may be the real active center in the process of propylene oxide polymerization.展开更多
基金supported by the(NRF)grants funded by the Ministry of Science,the ICT Future Planning(MSIP)of Korea under NRF-2016M3D1A1027663,NRF-2016M3D1A1027664(Future Materials Discovery Program),and NRF-2021R1A3B1076723(Research Leader Program)。
文摘Perovskite solar cells (PSCs) employing formamidinium lead iodide (FAPbI_(3)) have shown high efficiency.However,operational stability has been issued due to phase instability of α phase FAPbI_(3) at ambient temperature.Excess precursors in the perovskite precursor solution has been proposed to improve not only power conversion efficiency (PCE) but also device stability.Nevertheless,there is a controversial issue on the beneficial effect on PCE and/or stability between excess FAI and excess PbI_(2).We report here extended X-ray absorption fine structure (EXAFS) of FAPbI_(3) to study local structural change and explain the effect of excess precursors on photovoltaic performance and stability.Perovskite films prepared from the precursor solution with excess PbI_(2)shows better stability than those from the one with excess FAI,despite similar PCE.A rapid phase transition from α phase to non-perovskite δ phase is observed from the perovskite film formed by excess FAI.Furthermore,the (Pb-I) bond distance evaluated by the Pb L_(III)-edge EXAFS study is increased by excess FAI,which is responsible for the phase transition and poor device stability.This work can provide important insight into local structure-stability relation in the FAPbI_(3)-based PSCs.
文摘Effect of structure parameter n and its coupling with the connection mode among RuO6 octahedra of Srn＋1RUnO3n＋1 （n = 1, 2, ∞） are investigated. The gradually enhanced rotation and tilting effect with increasing n are observed in Srn＋1RUnO3n＋1. Besides, the chemical valence of Ru is not changed, while the one of Sr gradually varies with increasing n, which highlights the great contribution of connection mode to the chemical environment. Our results show a strong n dependence on the connection mode between octahedra in Srn＋1RUnO3n＋1 （n = 1, 2, ∞）.
基金Project supported by the National Natural Science FoundationNational Climbing Programme of China.
文摘Macrocycle compounds have great importance in host-guest chemistry and moleculeidentifications. 4-acetyl-bispyrazolones are a new type of polydentate ligands. Whenthey react with diamine compounds, new compounds or complexes containing C=O andC=N groups can be obtained. These compounds can be used to study the relationship ofcoordination structure and its properties, energy transferring processes between metal
文摘The effects of organic ethers such as diethyl ether, ethylene glycol diethyl ether and diethyl glycol diethyl ether on the structure of double metal cyanide complex catalyst and the structural changes of such catalyst in the process of propylene oxide polymerization were investigated by EXAFS. The results show that Co in all DMC catalysts is still coordinated by six cyanogens, while Zn is coordinated by O atom in organic complex. The more numerous the number of the ether bond, the higher the coordination numbers of O to Zn ion, the more active the catalyst we make. Five or six O atoms coordinated Zn ion may be the real active center in the process of propylene oxide polymerization.
基金supported by the National Natural Science Foundation of China(21373251)Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences,China(KZCX2-EW-307)~~
