Anthracene derivatives with strong spin–orbit coupling and efficient high-lying reverse intersystem crossing beyond the El-Sayed rule

Abstract

The attention to the materials with hot exciton channel and triplet-triplet fusion (TTF) mediated high-lying reverse intersystem crossing (hRISC) have been raised for their ability to convert non-emissive ‘dark’ triplets...

Quantitative Analysis of Exciton Dynamics: Investigating the Role of the Efficiency-Enhancement Layer for Blue Fluorescent Organic Light-Emitting Diodes

“…28−30 In Figure 4c, the MEL of Device A1 exhibits a typical TTF MEL fingerprint, sharply increasing at low magnetic fields (<50 mT) and decreasing at high magnetic fields (>50 mT), as only MADN is involved in the emission process. 30,31 However, as shown in Figure 4d,e, the MEL of Device B1 and Device C1 exhibits a different pattern with a sharp increase up to low magnetic fields (∼50 mT) and a slight rise up to high magnetic fields, indicating the presence of an hRISC channel in the MEL fingerprint. 32−34 In addition, the MEL intensity decreases with increasing voltage in the high magnetic field, which represents another MEL characteristic of TTF due to its electric-field-dependent process, ultimately confirming that the EEL device involves both the hRISC and TTF processes simultaneously.…”

“…These TT pairs are weakly exchange-coupled, allowing the ratio of TT pairs to be varied by an external magnetic field. Among them, only the singlet-featured 1 (TT) can transition to the singlet state. − In Figure c, the MEL of Device A1 exhibits a typical TTF MEL fingerprint, sharply increasing at low magnetic fields (<50 mT) and decreasing at high magnetic fields (>50 mT), as only MADN is involved in the emission process. , However, as shown in Figure d,e, the MEL of Device B1 and Device C1 exhibits a different pattern with a sharp increase up to low magnetic fields (∼50 mT) and a slight rise up to high magnetic fields, indicating the presence of an hRISC channel in the MEL fingerprint. − In addition, the MEL intensity decreases with increasing voltage in the high magnetic field, which represents another MEL characteristic of TTF due to its electric-field-dependent process, ultimately confirming that the EEL device involves both the hRISC and TTF processes simultaneously. Comparably, Device B1 with PAC as the EEL exhibits a relatively less decrease in MEL in the high magnetic field region, which might be attributed to the higher contribution to EL by the hRISC channel in PAC.…”