Polyimides based on rhenium(I) diimine complexes - Polyimides and Other High Temperature Polymers - page 94

Figure 5. Photocurrent response of Re-6FDA as a function of electric field strength at 488 and 514
nm.

the presence of an external electric field, into a free electron and a hole. The frac-
tion of absorbed photons that results in bound thermalized pairs is the primary
quantum yield

Φ ο . Under the assumption that primary quantum yield is independ-
ent of electric field and the distribution of bound pairs is spherically symmetric,
the photogeneration efficiency can be expressed by:

− 1

eEr

∞

e

2

eEr

Φ= Φ− (,) 1 rE

0

I I

0

(2)

g g

0 0

kT 4 πε ε kTr kT

g = 0

0 r 0

where I g is a recursive formula given by the equation:

I g +1 (x) = I g (x)-x g +1 exp(-x)/(g+1)!

(3)

with I 0 (x) = 1-exp(-x), Φ 0 is the primary yield of thermalized bound pairs, r 0 is the

initial thermalization separation between the bound charges, ε 0 is the permittivity

of free space, ε r is the relative permittivity and E is the applied electric field

strength. Figure 6 shows the theoretical curves for

Φ (r 0 ,E) as a function of E based