To Hop or Not to Hop? Understanding the Temperature Dependence of Spectral Diffusion in Organic Semiconductors

Title data

Athanasopoulos, Stavros ; Hoffmann, Sebastian T. ; Bässler, Heinz ; Köhler, Anna ; Beljonne, David:
To Hop or Not to Hop? Understanding the Temperature Dependence of Spectral Diffusion in Organic Semiconductors.
In: The Journal of Physical Chemistry Letters. Vol. 4 (2013) Issue 10 . - pp. 1694-1700.
ISSN 1948-7185
DOI: https://doi.org/10.1021/jz400480a

Official URL:

Abstract in another language

In disordered organic semiconductors, excited states and charges move by hopping in an inhomogeneously broadened density of states, thereby relaxing energetically (“spectral diffusion”). At low temperatures, transport can become kinetically frustrated and consequently dispersive. Experimentally, this is observed predominantly for triplet excitations and charges, and has not been reported for singlet excitations. We have addressed the origin of this phenomenon by simulating the temperature dependent spectral diffusion using a lattice Monte Carlo approach with either Miller–Abrahams or Förster type transfer rates. Our simulations are in agreement with recent fluorescence and phosphorescence experimental results. We show that frustrated and thus dispersive diffusion appears when the number of available hopping sites is limited. This is frequently the case for triplets that transfer by a short-range interaction, yet may also occur for singlets in restricted geometries or dilute systems. Frustration is lifted when more hopping sites become available, e.g., for triplets as a result of an increased conjugation in some amorphous polymer films.

Further data

Item Type:	Article in a journal
Refereed:	Yes
Keywords:	triplet/singlet exciton; kinetic frustration; charge transport; temperature dependence; semiconducting polymer; Monte Carlo simulations
Institutions of the University:	Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics II - Optoelectronics of Soft Matter > Chair Experimental Physics II - Optoelectronics of Soft Matter - Univ.-Prof. Dr. Anna Köhler Faculties Faculties > Faculty of Mathematics, Physics und Computer Science Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics II - Optoelectronics of Soft Matter
Result of work at the UBT:	Yes
DDC Subjects:	500 Science > 530 Physics
Date Deposited:	11 Feb 2015 12:09
Last Modified:	11 Feb 2015 12:09
URI:	https://eref.uni-bayreuth.de/id/eprint/6688