A simple picture of intrachain photophysics for a
conjugated polymer
1 Absorption can potentially occur at all
sites (if E>Egap)
2 Exciton formation (bound
"electron-hole“ pair) is rapid (subpicosecond)
3 Energy migration along chain to segment
with lowest energy band (tens of picoseconds)
4 Photoluminescence is dominated by emission
at longest conjugated segments.
(p*)
(p)
n=1
n=2
L
0
n=2
n=1
0
L''
n=1
n=2
0
L'
proportional to
L
-2
Energy
eigenvalues are
represents a distribution of effective conjugation
lengths.
Different crystalline
domains
Imagine a series of
one-dimensional potential wells which
a
Emission
Particle in a box
ØAbsorption (Abs) averages over all “chromophores”
while photoluminescence
(PL) identifies a small subset