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SUMMARY:Light-Conversion Mechanisms in Metal Halide Perovskites for Photov
 oltaics  - Prof Laura Herz (University of Oxford)
DTSTART:20190319T143000Z
DTEND:20190319T153000Z
UID:TALK120763@talks.cam.ac.uk
CONTACT:Emrys Evans
DESCRIPTION:Organic-inorganic metal halide perovskites have emerged as att
 ractive materials for solar cells with power-conversion efficiencies now e
 xceeding 22%. We discuss the fundamental processes that have enabled these
  materials to be such efficient light-harvesters and charge collectors. \n
 We demonstrate that at the intrinsic limit\, the mobility of charge-carrie
 rs is predominantly governed by interaction of carriers with optical vibra
 tions of the lead halide lattice (Fröhlich interaction)[1]. In the absenc
 e of trap-mediated charge recombination\, bimolecular (band-to-band) recom
 bination will dominate the charge-carrier losses near the Shockley-Queisse
 r limit. We show that in methylammonium lead triiodide perovskite\, such p
 rocesses can be fully explained as the inverse of absorption\,[2]  and exh
 ibit a dynamic that is heavily influences by photon reabsorption inside th
 e material.[3] Therefore\, predictions of intrinsic charge-carrier mobilit
 ies and recombination rates can be readily made from easily accessible par
 ameters\, such as photon absorption spectra\, phonon frequencies and the d
 ielectric function\, which allows for a targeted design of new materials f
 or solar energy harvesting.\nFinally\, we examine the prospect of such hig
 hly performing hybrid lead iodide perovskites in solar concentrator enviro
 nments.[4] We demonstrate that in the absence of degradation\, perovskite 
 solar cells can exhibit appreciably higher energy-conversion efficiencies 
 under solar concentration\, where they should be able to exceed the Shockl
 ey-Queisser limit and exhibit strongly elevated open-circuit voltages.[4\,
 5]\n[1]	 A.D. Wright\, C. Verdi\,  R.L. Milot\, G. E. Eperon\, M. A. Pére
 z-Osorio\, H. J. Snaith\, F. Giustino\, M. B. Johnston\, L. M. Herz\, Natu
 re Communications 2016\, 7\, 11755\n[2] 	C. L. Davies\, M. R. Filip\, J. B
 . Patel\, T. W. Crothers\, C. Verdi\, A. D. Wright\, R. L. Milot\, F.  Giu
 stino\, M. B. Johnston\, L. M. Herz\, Nature Communications 2018\, 9\, 293
 \n[3] 	T. W. Crothers\, R. L.  Milot\, J. B. Patel\, E. S. Parrott\, J.  S
 chlipf\, P.  Müller-Buschbaum\, M. B. Johnston\, L. M. Herz\, Nano Lett. 
 2017\, 17\, 5782\n[4] 	Q. Lin\, Z. Wang\, H. J. Snaith\, M. B. Johnston\, 
 L. M. Herz\, Advanced Science 2018\, 5 1700792\n[5]	Z. Wang\, Q. Lin\, B. 
 Wenger\, M. G. Christoforo\, Y. H. Lin\, M. T. Klug\, M. B. Johnston\, L. 
 M. Herz\, H. J. Snaith\, Nature Energy 2018\, DOI: 10.1038/s41560-018-0220
 -2
LOCATION:Rayleigh Seminar Room\, Maxwell Centre\, Cavendish Laboratory
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