Table 2.
Photophysical characteristics of compounds 2CzCN, ACzCN and PhCzCN and their solid mixtures with PO-T2T.
| Compound | λabsb, [nm] |
λPL, [nm] |
PLQYb, [%] |
ES, [eV] |
ET, [eV] |
ΔES-T, [eV] |
τ1 (χ2) a [ns] |
τ1/τ2/τ3 (χ2) b [ns] |
|---|---|---|---|---|---|---|---|---|
| 2CzCN | 363 | 396a/410b | 15 | 3.34 | 3.03 | 0.31 | 5.04 (1.001) |
1.35 (29%)/7.79(71%) (1.069) |
| ACzCN | 378 | 422a/424b | 7 | 3.33 | 3.04 | 0.29 | 4.46 (1.246) |
0.92 (59%)/5.54(41%) (1.057) |
| PhCzCN | 373 | 371, 387a/407b | 11 | 3.45 | 2.90 | 0.55 | 8.50 (1.108) |
0.80 (86%)/8.96(14%) (1.219) |
| 2CzCN:PO-T2T | – | 509b | 15 | 2.83 | 2.82 | 0.01 | – | 28 (13%)/902 (23%)/ 3045 (64%) (1.272) |
| ACzCN:PO-T2T | – | 552b | 14 | 2.62 | 2.56 | 0.06 | – | 42(9%)/1113(44%)/ 2865 (47%) (1.232) |
| PhCzCN:PO-T2T | – | 494b | 37 | 2.87 | 2.86 | 0.01 | – | 39(6%)/4288(94%)/- (1.104) |
λabs is the onset of the last absorption band; λPL is the fluorescence maxima; ES, ET are the energies of the first excited singlet and triplet states, estimated from the photoluminescence and phosphorescence measurements at 77 K (50 µ delay) and calculated by using the equation ES = 1240/λonset, PL, ET = 1240/λonset, PH; ΔES-T – singlet–triplet energy splitting; τ1/τ2/τ3 are the PL lifetimes. The decay profiles were fitted with residual values of 1.104–1.272.
a
Measured for dilute toluene solutions (10−5) of compounds.
b
Measured for solid films of compounds.