Ultrafast conductivity in a low-band-gap polyphenylene and fullerene blend studied by terahertz spectroscopy
Artikel i vetenskaplig tidskrift, 2009

Time-resolved terahertz spectroscopy and Monte Carlo simulations of charge-carrier motion are used to investigate photoinduced transient conductivity in a blend of a low-band-gap polyphenylene copolymer and fullerene derivative. The optical excitation pulse generates free holes delocalized on polymer chains. We show that these holes exhibit a very high initial mobility as their initial excess energy facilitates their transport over defects (potential barriers) on polymer chains. The conductivity then drops down rapidly within 1 ps, and we demonstrate that this decrease occurs essentially by two mechanisms. First, the carriers loose their excess energy and they thus become progressively localized between the on-chain potential barriers-this results in a mobility decay with a rate of (180 fs)(-1). Second, carriers are trapped at defects (potential wells) with a capture rate of (860 fs)(-1). At longer time scales, populations of mobile and trapped holes reach a quasiequilibrium state and further conductivity decrease becomes very slow.

polythiophene

time

terahertz wave spectra

charge-carrier mobility

dynamics

resolved spectra

photoconductivity

photogeneration

fullerenes

disorder

hole mobility

time

Monte Carlo methods

energy gap

bulk heterojunction

conjugated polymers

transport

polymer blends

chains

Författare

H. Nemec

H. K. Nienhuys

Erik Per Perzon

Chalmers, Kemi- och bioteknik, Polymerteknologi

Fengling Zhang

Olle Inganäs

P. Kuzel

V. Sundstrom

Physical Review B - Condensed Matter and Materials Physics

1098-0121 (ISSN)

Vol. 79 24 245326 (art no)-

Ämneskategorier

Den kondenserade materiens fysik

DOI

10.1103/PhysRevB.79.245326

Mer information

Skapat

2017-10-08