Triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes.
The triplet to singlet exciton formation ratio in a MEH-PPV light-emitting diode is measured by comparing the triplet-induced absorptions with optical and electric excitations at the same singlet exciton density. The ratio is a strong universal decreasing function of the averaged electric field. Using 4 ns for singlet to triplet intersystem crossing time, the ratio is significantly larger than the spin-independent value 3 at intermediate field but is reduced to about 2 for higher field.
Lin
L C
LC
Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan, Republic of China.
Meng
H F
HF
Shy
J T
JT
Horng
S F
SF
Yu
L S
LS
Chen
C H
CH
Liaw
H H
HH
Huang
C C
CC
Peng
K Y
KY
Chen
S A
SA