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SUMMARY:Tunable photostriction of halide perovskites controlled by light: 
 Light-induced lattice expansion or light-induced lattice contraction? - Bo
  Peng\, Materials Theory Group and Theory of Condensed Matter Group
DTSTART:20201125T113000Z
DTEND:20201125T123000Z
UID:TALK154138@talks.cam.ac.uk
CONTACT:Angela Harper
DESCRIPTION:Recently it is debated whether the light-induced expansion in 
 halide\nperovskites is driven by photoexcitation or by thermal effects [Sc
 ience\n368\, eaay8691 (2020) & 368\, eaba6295 (2020)]. In addition\, it re
 mains\nunclear whether light can induce lattice expansion or lattice\ncont
 raction because contradictory results on photostriction of\nperovskites ha
 ve been obtained in previous experiments. Here we find\nthat photo-induced
  strain can be controlled by selective excitation of\nvalence states using
  first principles calculations. The overall effect\nis that light induces 
 lattice contraction at weak excitation\, while\nlattice expansion occurs a
 t strong excitation. Such uniform\nstrain controlled by light can be used 
 as an ultrafast approach to\noptimize the optoelectronic performance and t
 o improve the stability of\nhalide perovskites.\n\nJoin Zoom Meeting:\nhtt
 ps://bham-ac-uk.zoom.us/j/85702415099?pwd=VTh5aFZ4Sm9Nc1dxZXYwelJpc1JtZz09
 \nMeeting ID: 857 0241 5099\nPasscode: 501623
LOCATION:Zoom
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