9 Photosynergetic Effects on Triplet–Triplet Annihilation …
163
(I)
(II)
(III)
(IV)
Fig. 9.9 TTA reaction time, τ TTA = 1/k TTA , [ns] for DPA (I) and Cn-sDPAs (II). Here, red, gray,
blue, orange, and cyan colors represent monomer A, B, C, D, and E respectively. Corresponding
TTET reaction time, τ TTET = 1/k TTET , [μs] for DPA (III) and Cn-sDPAs (IV). Reprinted with
permission from [28] Copyright 2019. American Chemical Society
two triplet excitons locate at any neighboring site because of τ TTA << τ TTET . Another
finding is that there exist preferable directions both for TTA and TTET. For DPA, TTA
between B and C monomers are so fast (fs time scale), and others are ns time scale
and comparable with the minimum time of TTA in C7-sDPA. Among four directions,
the ratio between the minimum reaction time and the second minimum one is about
1:10. It means that the triplet energy transfer occurs quasi-two-dimensionally.
For C7-sDPA, the situation is different from DPA. One of the TTA reaction times
of C7-sDPA (A–B pair) is ns time scale, while the others are much longer than it.
This behavior is also found for the TTET process. However, comparing to DPA,
the minimum reaction time of the TTET process is shorter than those of the TTA
reaction times except for that in the A–B pair. This indicates that TTA occurs only
163
(I)
(II)
(III)
(IV)
Fig. 9.9 TTA reaction time, τ TTA = 1/k TTA , [ns] for DPA (I) and Cn-sDPAs (II). Here, red, gray,
blue, orange, and cyan colors represent monomer A, B, C, D, and E respectively. Corresponding
TTET reaction time, τ TTET = 1/k TTET , [μs] for DPA (III) and Cn-sDPAs (IV). Reprinted with
permission from [28] Copyright 2019. American Chemical Society
two triplet excitons locate at any neighboring site because of τ TTA << τ TTET . Another
finding is that there exist preferable directions both for TTA and TTET. For DPA, TTA
between B and C monomers are so fast (fs time scale), and others are ns time scale
and comparable with the minimum time of TTA in C7-sDPA. Among four directions,
the ratio between the minimum reaction time and the second minimum one is about
1:10. It means that the triplet energy transfer occurs quasi-two-dimensionally.
For C7-sDPA, the situation is different from DPA. One of the TTA reaction times
of C7-sDPA (A–B pair) is ns time scale, while the others are much longer than it.
This behavior is also found for the TTET process. However, comparing to DPA,
the minimum reaction time of the TTET process is shorter than those of the TTA
reaction times except for that in the A–B pair. This indicates that TTA occurs only