BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:Microstructural Control of Charge Generation in Organic Solar Cell
 s
DTSTART:20141211T163000
DTEND:20141211T173000
DTSTAMP:20260414T211951Z
UID:6c96dd8b78eb66a9574f8249ec133d136fd89fc72563eb98b1d6b642
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Natali Banerji\, University of Fribourg\nIn organic sola
 r cells\, excitons are dissociated by charge separation between an electro
 n donor (e.g. conjugated polymer) and an electron acceptor (e.g. fullerene
  derivative). For solid-state blends of the two components\, their precise
  arrangement into a bulk heterojunction (BHJ) plays an important role\, an
 d this microstructure was recently revealed to be very complex. Not only c
 an the polymer and fullerene arrange into either amorphous or crystalline 
 neat domains of variable size\, but an additional intimately mixed polymer
 -fullerene phase has been identified.\nWe show here that microstructure an
 d photophysical properties in polymer:fullerene blends go hand-in-hand to 
 determine the efficiency of organic solar cells. Ultrafast transient absor
 ption\, electro-absorption and fluorescence up-conversion spectroscopy wer
 e used to investigate the dynamics of charge separation in samples with we
 ll-characterized microstructures. Blends of the pBTTT and PBDTTPD polymers
  with PCBM gave us access to different scenarios\, such as a single intima
 tely mixed polymer:fullerene phase\, an intermixed phase with additional p
 ure PCBM clusters\, or a three-phase microstructure of pure polymer aggreg
 ates\, pure fullerene clusters and intermixed regions.\nMoreover\, we have
  selectively excited either the fullerene or the polymer in order to evalu
 ate the effect of microstructure on both the electron and hole transfer pa
 thways. We discuss how an ideal microstructure can promote generation of f
 ree charge carriers and relate the high photovoltaic performance of the PB
 DTTPD blend (up to 8.5 %) to its favorable properties in terms of microstr
 ucture and exciton delocalization.\nBio: Prof. Natalie Banerji joined the 
 University of Fribourg\, Switzerland\, as an Associate Professor in Septem
 ber 2014. Previously (2011-2014)\, she held an autonomously funded project
 -leader position (SNSF Ambizione Fellowship) at EPFL. Between 2009 and 201
 1\, she was a SNSF post-doctoral fellow in the group of Professor Alan J. 
 Heeger at the University of California\, Santa Barbara. She obtained her P
 h. D. degree in Chemistry at the University of Geneva\, Switzerland\, in 2
 009. Her research interests include ultrafast spectroscopy and photophysic
 s of organic electronic materials
LOCATION:CH G1 495 https://plan.epfl.ch/?room==CH%20G1%20495
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR