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Author Shi, W.; Callewaert, V.; Barbiellini, B.; Saniz, R.; Butterling, M.; Egger, W.; Dickmann, M.; Hugenschmidt, C.; Shakeri, B.; Meulenberg, R. W.; Brück, E.; Partoens, B.; Bansil, A.; Eijt, S.W. H. pdf  url
doi  openurl
  Title Nature of the Positron State in CdSe Quantum Dots Type A1 Journal article
  Year (down) 2018 Publication Physical review letters Abbreviated Journal Phys Rev Lett  
  Volume 121 Issue 5 Pages 057401  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract Previous studies have shown that positron-annihilation spectroscopy is a highly sensitive probe of the electronic structure and surface composition of ligand-capped semiconductor quantum dots (QDs) embedded in thin films. The nature of the associated positron state, however, whether the positron is confined inside the QDs or localized at their surfaces, has so far remained unresolved. Our positron-annihilation lifetime spectroscopy studies of CdSe QDs reveal the presence of a strong lifetime component in the narrow range of 358–371 ps, indicating abundant trapping and annihilation of positrons at the surfaces of the QDs. Furthermore, our ab initio calculations of the positron wave function and lifetime employing a recent formulation of the weighted density approximation demonstrate the presence of a positron surface state and predict positron lifetimes close to experimental values. Our study thus resolves the long-standing question regarding the nature of the positron state in semiconductor QDs and opens the way to extract quantitative information on surface composition and ligand-surface interactions of colloidal semiconductor QDs through highly sensitive positron-annihilation techniques.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000440635300012 Publication Date 2018-08-02  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9007 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 8.462 Times cited 6 Open Access  
  Notes The work at Delft University of Technology was supported by the China Scholarship Council (CSC) grant of W. S. We acknowledge financial support for this research from ADEM, A green Deal in Energy Materials of the Ministry of Economic Affairs of The Netherlands. The PALS study is based upon experiments performed at the PLEPS instrument of the NEPOMUC facility at the Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, and was supported by the European Commission under the 7th Framework Program, Key Action: Strengthening the European Research Area, Research Infrastructures, Contract No. 226507, NMI3. The work at the University of Maine was supported by the National Science Foundation under Grant No. DMR-1206940. V. C. and R. S. were supported by the FWO-Vlaanderen through Project No. G. 0224.14N. Computational resources and services used in this work were in part provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the FWO-Vlaanderen and the Flemish Government (EWI Department). The work at Northeastern University was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences Grant No. DE-FG02-07ER46352 (core research), and benefited from Northeastern University’s Advanced Scientific Computation Center (ASCC), the National Energy Research Scientific Computing Center (NERSC) through DOE Grant No. DE-AC02-05CH11231, and support (functionals for modeling positron spectros- copies of layered materials) from the DOE EFRC: Center for the Computational Design of Functional Layered Materials (CCDM) under DE-SC0012575. Approved Most recent IF: 8.462  
  Call Number CMT @ cmt @c:irua:152999UA @ admin @ c:irua:152999 Serial 5009  
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Author Eijt, S.W.H.; Shi, W.; Mannheim, A.; Butterling, M.; Schut, H.; Egger, W.; Dickmann, M.; Hugenschmidt, C.; Shakeri, B.; Meulenberg, R.W.; Callewaert, V.; Saniz, R.; Partoens, B.; Barbiellini, B.; Bansil, A.; Melskens, J.; Zeman, M.; Smets, A.H.M.; Kulbak, M.; Hodes, G.; Cahen, D.; Brück, E. url  doi
openurl 
  Title New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy Type A1 Journal article
  Year (down) 2017 Publication Journal of physics : conference series Abbreviated Journal  
  Volume 791 Issue 791 Pages 012021  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000400610500021 Publication Date 2017-02-22  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1742-6588 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor Times cited 1 Open Access  
  Notes The work at Delft University of Technology was supported by the China Scholarship Council (CSC) grant of W.S., by ADEM, A green Deal in Energy Materials of the Ministry of Economic Affairs of The Netherlands (www.adem- innovationlab.nl), and the STW Vidi grant of A.S., Grant No. 10782. The PALS study is based upon experiments performed at the PLEPS instrument of the NEPOMUC facility at the Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, and was supported by the European Commission under the 7 th Framework Programme, Key Action: Strengthening the European Research Area, Research Infrastructures, Contract No. 226507, NMI3. The work at University of Maine was supported by the National Science Foundation under Grant No. DMR-1206940. Research at the University of Antwerp was supported by FWO grants G022414N and G015013. The work at Northeastern University was supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences grant number DE-FG02-07ER46352 (core research), and benefited from Northeastern University's Advanced Scientific Computation Center (ASCC), the NERSC supercomputing center through DOE grant number DE-AC02-05CH11231, and support (applications to layered materials) from the DOE EFRC: Center for the Computational Design of Functional Layered Materials (CCDM) under DE-SC0012575. The work at the Weizmann Institute was supported by the Sidney E. Frank Foundation through the Israel Science Foundation, by the Israel Ministry of Science, and the Israel National Nano-Initiative. D.C. holds the Sylvia and Rowland Schaefer Chair in Energy Research. Approved Most recent IF: NA  
  Call Number CMT @ cmt @ c:irua:140850 Serial 4426  
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