Epitaxial heterostructures based on organicinorganic hybrid perovskites and two-dimensional materials hold great promises in optoelectronics, but they have been prepared only via solid-state methods that restricted th...Epitaxial heterostructures based on organicinorganic hybrid perovskites and two-dimensional materials hold great promises in optoelectronics, but they have been prepared only via solid-state methods that restricted their practical applications. Herein, we report cubic-phased MAPbBr3(MA=CH3NH3+) nanocrystals were epitaxially deposited on trigonal/hexagonal-phased MoS2 nanosheets in solution by facilely tuning the solvation conditions. In spite of the mismatched lattice symmetry between the square MAPbBr3(001) overlayer and the hexagonal MoS2(001) substrate, two different aligning directions with lattice mismatch of as small as 1% were observed based on the domainmatching epitaxy. This was realized most likely due to the flexible nature and absence of surface dangling bonds of MoS2 nanosheets. The formation of the epitaxial interface affords an effective energy transfer from MAPbBr3 to MoS2, and as a result, paper-based photodetectors facilely fabricated from these solution-dispersible heterostructures showed better performance compared to those based on MoS2 or MAPbBr3 alone. In addition to the improved energy transfer and light adsorption, the use of MoS2 nanosheets provided flexible and continuous substrates to connect the otherwise discrete MAPbBr3 nanocrystals and achieved the better film forming ability. Our work suggests that the scalable preparation of heterostructures based on organic-inorganic hybrid perovskites and 2D materials via solution-phase epitaxy may bring about more opportunities for expanding their optoelectronic applications.展开更多
Multicolor luminescent rare-earth ion-doped Y2O3 nanocrystals （NCs） were prepared by a solvethermal method. The as-synthesized NCs yielded nanosheets, nanowires （NWs） and nanorods （NRs） with the increase of alka...Multicolor luminescent rare-earth ion-doped Y2O3 nanocrystals （NCs） were prepared by a solvethermal method. The as-synthesized NCs yielded nanosheets, nanowires （NWs） and nanorods （NRs） with the increase of alkali （NaOH） in oleic acid system. Moreover, Y203 nanowires with controllable size have also been obtained. After sintering, the PL intensity of Y2O3：Ln3＋ nanocrystals increased with the changed morphology of the precursor, that is, Y（OH）3 nanocrystals. Both downconversion （red emission for Y2O3：Eu3＋ and green emission for Y2O3：Tb3＋） and upconversion （red emission for Y2O3：Yb/Er3＋） luminescence of the as-prepared nanocrystals have been demonstrated in this work. We also found that the PL intensity of Y2O3：Ln3＋ NCs dispersed in polar solvent was stronger than that in nonpolar solvent. Their up/downconversion fluorescence and controllable morphology might promise further fundamental research and biochemistry such as nanoscale optoelectronics, nanolasers, and ultrasensitive multicolor biolables.展开更多
The design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic cou...The design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic counterparts. Here, we report a new approach to achieving such a goal by growing CdS quantum dots （QDs） within single crystals of lysozyme protein. This bio-nano hybrid emitted much stronger red fluorescence than its counterpart without the crystal, and such fluorescence properties could be either enhanced or suppressed by the addition of Ag（I） or Hg（II）, respectively. The three-dimensional incorporation of CdS QDs within the lysozyme crystals was revealed by scanning transmission electron microscopy with electron tomography. More importantl~ since our approach did not disrupt the crystalline nature of the lysozyme crystals, the metal and protein interactions were able to be studied by X-ray crystallography, thus providing insight into the role of Cd（II） in the CdS QDs formation.展开更多
基金supported by the National Natural Science Foundation of China (51322202) the Young 1000 Talents Global Recruitment Program of China+2 种基金the financial support from Macao Science and Technology Development Fund (FDCT-116/2016/A3 and FDCT-091/2017/A2)Research Grant (SRG2016-00087-FST) from the University of Macao, the Natural Science Foundation of China (91733302, 61605073 and 2015CB932200)the Young 1000 Talents Global Recruitment Program of China
文摘Epitaxial heterostructures based on organicinorganic hybrid perovskites and two-dimensional materials hold great promises in optoelectronics, but they have been prepared only via solid-state methods that restricted their practical applications. Herein, we report cubic-phased MAPbBr3(MA=CH3NH3+) nanocrystals were epitaxially deposited on trigonal/hexagonal-phased MoS2 nanosheets in solution by facilely tuning the solvation conditions. In spite of the mismatched lattice symmetry between the square MAPbBr3(001) overlayer and the hexagonal MoS2(001) substrate, two different aligning directions with lattice mismatch of as small as 1% were observed based on the domainmatching epitaxy. This was realized most likely due to the flexible nature and absence of surface dangling bonds of MoS2 nanosheets. The formation of the epitaxial interface affords an effective energy transfer from MAPbBr3 to MoS2, and as a result, paper-based photodetectors facilely fabricated from these solution-dispersible heterostructures showed better performance compared to those based on MoS2 or MAPbBr3 alone. In addition to the improved energy transfer and light adsorption, the use of MoS2 nanosheets provided flexible and continuous substrates to connect the otherwise discrete MAPbBr3 nanocrystals and achieved the better film forming ability. Our work suggests that the scalable preparation of heterostructures based on organic-inorganic hybrid perovskites and 2D materials via solution-phase epitaxy may bring about more opportunities for expanding their optoelectronic applications.
文摘Multicolor luminescent rare-earth ion-doped Y2O3 nanocrystals （NCs） were prepared by a solvethermal method. The as-synthesized NCs yielded nanosheets, nanowires （NWs） and nanorods （NRs） with the increase of alkali （NaOH） in oleic acid system. Moreover, Y203 nanowires with controllable size have also been obtained. After sintering, the PL intensity of Y2O3：Ln3＋ nanocrystals increased with the changed morphology of the precursor, that is, Y（OH）3 nanocrystals. Both downconversion （red emission for Y2O3：Eu3＋ and green emission for Y2O3：Tb3＋） and upconversion （red emission for Y2O3：Yb/Er3＋） luminescence of the as-prepared nanocrystals have been demonstrated in this work. We also found that the PL intensity of Y2O3：Ln3＋ NCs dispersed in polar solvent was stronger than that in nonpolar solvent. Their up/downconversion fluorescence and controllable morphology might promise further fundamental research and biochemistry such as nanoscale optoelectronics, nanolasers, and ultrasensitive multicolor biolables.
基金This work was supported by the US National Science Foundation （Nos. CMMI 0749028 and DMR-0117792）. The authors thank C. Lei and W. Swiech for help with the STEM imaging, C~ M. Bee and D. Zhang for fluorescence microscopic measurements, S. M. Nie for the use of Nuance system and A. M. Smith for insightful discussions. S. H. and I. M. R. acknowledge support from the US Department of Energy （grant No. DE-FC36-05GO15064）. STEM experiments were carried out in part in the Frederick Seitz Materials Research Laboratory Central Facilities, University of Illinois. X-ray crystallographic data for this study were measured at beamline X12C of the National Synchrotron Light Source, Brookhaven National Laboratory. Financial support comes principally from the Offices of Biological and Environmental Research and of Basic Energy Sciences of the US Department of Energy, and from the National Center for Research Resources （No. P41RR012408） and the National Institute of General Medical Sciences （No. P41GM103473） of the National Institutes of Health.
文摘The design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic counterparts. Here, we report a new approach to achieving such a goal by growing CdS quantum dots （QDs） within single crystals of lysozyme protein. This bio-nano hybrid emitted much stronger red fluorescence than its counterpart without the crystal, and such fluorescence properties could be either enhanced or suppressed by the addition of Ag（I） or Hg（II）, respectively. The three-dimensional incorporation of CdS QDs within the lysozyme crystals was revealed by scanning transmission electron microscopy with electron tomography. More importantl~ since our approach did not disrupt the crystalline nature of the lysozyme crystals, the metal and protein interactions were able to be studied by X-ray crystallography, thus providing insight into the role of Cd（II） in the CdS QDs formation.
