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UID:ucr_events_53003356243620@highlanderhub.app
DTSTAMP:20260531T005646Z
DTSTART:20260601T180000Z
DTEND:20260601T190000Z
SUMMARY:ECE Seminar Series: Dr. Luke Daemen (UCR)
DESCRIPTION:Flyer: Singlet Fission in Organic Semiconductors: Observation o
 f the Triplet Excitonic In Acenes with Neutron Vibrational Spectroscopy\n\
 nAbstract: Photovoltaics (PV) convert sunlight into electricity with zero 
 emissions\, providing technical solutions for the world’s ever-growing e
 nergy demand while simultaneously preventing climate change from carbon di
 oxide emissions. The Shockley−Queisser limit puts the maximum theoretica
 l single junction PV device efficiency at ∼33%. Typical crystalline or p
 olycrystalline silicon solar panels have an efficiency closer to 20% with 
 higher performance -but more expensive- systems demonstrated. Organic semi
 conductors present a number of advantages over silicon for various applica
 tions including photovoltaics: lightweight\, mechanical flexibility\, tuna
 bility\, and integrability with other materials and systems. Perhaps the g
 reatest advantage is the promise of increased efficiency compared to the p
 resent Si-based technology. Singlet fission (SF) is a spin-allowed process
  that converts a singlet exciton into a pair of triplet excitons between m
 olecular organic chromophores. This carrier multiplication process increas
 es the maximum theoretical PV efficiency to ∼44%. Converting a single ph
 oton into a pair of excited charges spurred research into the use of SF mo
 lecules to improve photovoltaic device efficiency\, as the ability to over
 come the Shockley−Queisser limit would have profound impacts on the pric
 e and land use of photovoltaic energy generation. While SF is not fully un
 derstood\, many studies have been dedicated to molecules that can undergo 
 SF and into incorporating SF into devices for increased efficiencies inclu
 ding photovoltaics\, photodetectors\, and organic light emitting diodes. N
 eutron vibrational spectroscopy in conjunction with high-performance compu
 ting and time-dependent density functional theory was used to observe the 
 formation of the triplet state in tetracene and pentacene The spectroscopi
 c results reveal intermolecular structural relaxation due to the presence 
 of a triplet excited state. The structural dynamics of the combined excite
 d state molecule and surrounding tetracene molecules are further studied u
 sing time-dependent density functional theory which shows that the singlet
  and triplet levels shift due to the excited state geometry\, reducing the
  uphill energy barrier for SF.
LOCATION:Winston Chung Hall\, 205/206
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