Eu3＋-activated layered LnOCI （Ln=La and Gd） phosphors were synthesized by the conventional solid-state method at relatively low temperature （700 ℃） and shorter duration of 2 h. The structural parameters were ref...Eu3＋-activated layered LnOCI （Ln=La and Gd） phosphors were synthesized by the conventional solid-state method at relatively low temperature （700 ℃） and shorter duration of 2 h. The structural parameters were refined by the Rietveld refinement analysis and confirmed by the high resolution transmission electron microscopy （HRTEM）. Both the compounds were crystallized in the tetragonal structure with space group P4/nmm （No. 129）. The homogeneity of the elements were ana- lyzed by TEM mapping and found to be uniformly distributed. The photoluminescence spectra revealed that the intensity of 5D0--7F2 transition （619 nm） was more intense in Eu3＋-activated GdOC1 compared to LaOC1. This was due to the property of Gd3＋ ions to act as an intermediate sublattice to facilitate the energy transfer to Eu3＋ ions. Intensity parameters and radiative properties such as transition probabilities, radiative lifetime and branching ratio were calculated using the Judd-Ofelt theory. The CIE color coordinates result revealed that the Eu3＋-activated GdOC1 （0.641, 0.354） phosphor was close to the commercial red phosphors like, Y203：Eu3＋ （0.645, 0.347）, Y202S：Eu3＋ （0.647, 0.343） and National Television System Committee （NTSC） （0.67, 0.33）. The results suggest that the present GdOCI：Eu3＋ compound acts as a potential candidate for red phosphor materials.展开更多
Flexible,large-area,and stable perovskite photodetectors have drawn increasing widespread research attention for next-generation wearable and portable optoelectronic devices.However,high mechanical durability coupled ...Flexible,large-area,and stable perovskite photodetectors have drawn increasing widespread research attention for next-generation wearable and portable optoelectronic devices.However,high mechanical durability coupled with large device area and enhanced environmental stability has not been demonstrated yet to attain practical viability.Herein,a highly bendable,stable,and large-area(3 cm^(2))flexible polystyrene incorporated perovskite photodetector is presented.Due to the formation of a porous polystyrene-perovskite composite film in a single step it allows unprecedented mechanical stability,maintaining 85%of its original photocurrent value after 10,000 bending cycles at a bending angle of 120°.Equally crucial,the solution-processed self-assembled Pt-Au nanochains were developed to provide a simple and fast method of patterning the conductive and flexible electrodes onto the filter substrate.The optimized polystyrene-perovskite photodetector exhibits a high responsivity up to 2.73 A W^(−1),a maximum specific detectivity of 6.2×10^(13) Jones,and a superior switching ratio of 1.0×10^(4).In addition,the polystyrene-perovskite photodetector yields excellent stability under the combined stresses of moisture,ambient air,and room light,and retains 92%of its original performance for over 30 days.All these results demonstrate that this work provides a facile and cost-effective approach that paves the way to develop high-performance,stable,and highly flexible optoelectronic devices.展开更多
文摘Eu3＋-activated layered LnOCI （Ln=La and Gd） phosphors were synthesized by the conventional solid-state method at relatively low temperature （700 ℃） and shorter duration of 2 h. The structural parameters were refined by the Rietveld refinement analysis and confirmed by the high resolution transmission electron microscopy （HRTEM）. Both the compounds were crystallized in the tetragonal structure with space group P4/nmm （No. 129）. The homogeneity of the elements were ana- lyzed by TEM mapping and found to be uniformly distributed. The photoluminescence spectra revealed that the intensity of 5D0--7F2 transition （619 nm） was more intense in Eu3＋-activated GdOC1 compared to LaOC1. This was due to the property of Gd3＋ ions to act as an intermediate sublattice to facilitate the energy transfer to Eu3＋ ions. Intensity parameters and radiative properties such as transition probabilities, radiative lifetime and branching ratio were calculated using the Judd-Ofelt theory. The CIE color coordinates result revealed that the Eu3＋-activated GdOC1 （0.641, 0.354） phosphor was close to the commercial red phosphors like, Y203：Eu3＋ （0.645, 0.347）, Y202S：Eu3＋ （0.647, 0.343） and National Television System Committee （NTSC） （0.67, 0.33）. The results suggest that the present GdOCI：Eu3＋ compound acts as a potential candidate for red phosphor materials.
文摘Flexible,large-area,and stable perovskite photodetectors have drawn increasing widespread research attention for next-generation wearable and portable optoelectronic devices.However,high mechanical durability coupled with large device area and enhanced environmental stability has not been demonstrated yet to attain practical viability.Herein,a highly bendable,stable,and large-area(3 cm^(2))flexible polystyrene incorporated perovskite photodetector is presented.Due to the formation of a porous polystyrene-perovskite composite film in a single step it allows unprecedented mechanical stability,maintaining 85%of its original photocurrent value after 10,000 bending cycles at a bending angle of 120°.Equally crucial,the solution-processed self-assembled Pt-Au nanochains were developed to provide a simple and fast method of patterning the conductive and flexible electrodes onto the filter substrate.The optimized polystyrene-perovskite photodetector exhibits a high responsivity up to 2.73 A W^(−1),a maximum specific detectivity of 6.2×10^(13) Jones,and a superior switching ratio of 1.0×10^(4).In addition,the polystyrene-perovskite photodetector yields excellent stability under the combined stresses of moisture,ambient air,and room light,and retains 92%of its original performance for over 30 days.All these results demonstrate that this work provides a facile and cost-effective approach that paves the way to develop high-performance,stable,and highly flexible optoelectronic devices.
