How do Triplets and Charges Move in Disordered Organic Semiconductors? A Monte Carlo Study Comprising the Equilibrium and Nonequilibrium Regime

Title data

Hoffmann, Sebastian T. ; Athanasopoulos, Stavros ; Beljonne, David ; Bässler, Heinz ; Köhler, Anna:
How do Triplets and Charges Move in Disordered Organic Semiconductors? A Monte Carlo Study Comprising the Equilibrium and Nonequilibrium Regime.
In: The Journal of Physical Chemistry C. Vol. 116 (2012) Issue 31 . - pp. 16371-16383.
ISSN 1932-7455
DOI: https://doi.org/10.1021/jp305062p

Official URL:

Abstract in another language

We have investigated how electronic excitations that couple via short-range interaction, i.e., triplet excitations and charge carriers, move in a disordered organic semiconductor. In this systematic study, we paid special emphasis to the transition from quasi-equilibrium to nonequilibrium transport as the temperature is lowered from 300 to 10 K. As a method, we used Monte Carlo simulations employing both Marcus as well as Miller–Abrahams (MA) transition rates. The simulation parameters are the degree of static energetic disorder, the geometric reorganization energy, and the degree of electronic coupling among the hopping sites. In the case of conjugated polymers, the effects of intrachain versus interchain transport are taken into account. In the simulations, we monitor the spectral relaxation of excitations as well as their diffusivity. We find that, below a disorder controlled transition temperature, transport becomes kinetically frustrated and, concomitantly, dispersive. In this temperature regime, transport is controlled by single phonon tunneling, tractable in terms of MA rates, while in the high temperature regime multiphonon hopping, described by Marcus rates, prevails. The results also provide a quantitative assessment of dispersive excitation transport within the intermediate temperature regime in which no analytic theory is available so far. Quantitative agreement between simulation and previous experiments allows one to extract system parameters such as the minimum hopping time and to delineate the parameter range in which Marcus and MA rates should be used in transport studies.

Further data

Item Type:	Article in a journal
Refereed:	Yes
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 12:28
Last Modified:	11 Feb 2015 12:28
URI:	https://eref.uni-bayreuth.de/id/eprint/6697