The mechanism of long-range exciton diffusion in a nematically organized porphyrin layer.
The exciton diffusion length in a nematically organized meso-tetra(4-n-butylphenyl)porphyrin (TnBuPP) layer was found to exceed 40 nm at a temperature of 90 K and to be equal to 22 +/- 3 nm at 300 K. The exciton diffusion coefficient decreases from > or = 3.1 x 10(-6) m(2)/s at 90 K to (2.5 +/- 0.5) x 10(-7) m(2)/s at 300 K. This thermal deactivation is attributed to exciton motion via a band mechanism. The motion of an exciton is not limited by polaronic effects; that is, the deformation of the atomic lattice around the exciton. The absence of polaronic self-trapping implies that the exciton diffusion coefficient can be enhanced by improvement of structural order and rigidity of the material.
Huijser
Annemarie
A
Opto-Electronic Materials Section, DelftChemTech, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands.
Savenije
Tom J
TJ
Meskers
Stefan C J
SC
Vermeulen
Martien J W
MJ
Siebbeles
Laurens D A
LD