Ultra-fast triplet-triplet-annihilation-mediated high-lying reverse intersystem crossing triggered by participation of nπ*-featured excited states

Abstract

The harvesting of ‘hot’ triplet excitons through high-lying reverse intersystem crossing mechanism has emerged as a hot research issue in the field of organic light-emitting diodes. However, if high-lying reverse intersystem crossing materials lack the capability to convert ‘cold’ T1 excitons into singlet ones, the actual maximum exciton utilization efficiency would generally deviate from 100%. Herein, through comparative studies on two naphthalimide-based compounds CzNI and TPANI, we revealed that the ‘cold’ T1 excitons in high-lying reverse intersystem crossing materials can be utilized effectively through the triplet-triplet annihilation-mediated high-lying reverse intersystem crossing process if they possess certain triplet-triplet upconversion capability. Especially, quite effective triplet-triplet annihilation-mediated high-lying reverse intersystem crossing can be triggered by endowing the high-lying reverse intersystem crossing process with a 3ππ*→1nπ* character. By taking advantage of the permanent orthogonal orbital transition effect of 3ππ*→1nπ*, spin–orbit coupling matrix elements of ca. 10 cm−1 can be acquired, and hence ultra-fast mediated high-lying reverse intersystem crossing process with rate constant over 109 s−1 can be realized.

Organic All-Photonic Artificial Synapses Enabled by Anti-Stokes Photoluminescence

“…In the process of TTA, both 1 (TT) and 3 (TT) will be obtained, when the energy levels meet the criterion that 2 E T 1 ≥ E S m and 2 E T 1 ≥ E T n . In our system, 2 E T 1 was not smaller than T 2 –T 9 , triplet-featuring 3 (TT) states could greatly yield T 9 since the T 1 → T 9 ESA peak was observed in the TA spectrum, and the μ and f between T 1 and T 9 were large …”

“…57 In our system, 2E Td 1 was not smaller than T 2 −T 9 , triplet-featuring 3 (TT) states could greatly yield T 9 since the T 1 → T 9 ESA peak was observed in the TA spectrum, and the μ and f between T 1 and T 9 were large. 58 There is no doubt that the triplet states will react with 3 O 2 to yield 1 O 2 in an ambient atmosphere, so most TTA occurs in anaerobic conditions. To investigate the observed linear to quadratic excitation−emission relationship change in aerobic conditions, the excitation-dependent emission intensity was characterized in an anaerobic system (Figure S31a).…”

Asymmetric anthracene hosts decorated with naphthobenzofurocarbazole for highly efficient deep-blue organic light-emitting diodes and low-efficiency roll-off

“…Under the condition T 1 < S 1 < 2*T 1 < T 2 , the singlet generated by TTF causes the DF portion ( f DF ) to have a maximum value of 60% (37.5/(25 + 37.5) = 0.6). 24,37 However, as shown in Fig. 8(c), the f DF values of ATPNF-1 -ND and ATPNF-2 -ND were 28.1% and 31.9%, respectively, much lower than the maximum f DF of 60%.…”

Regulation of various photo-active UOPs in a polymer matrix by tuning intermolecular charge transfer

“…64,65 The T 1 and S 1 states mainly characterized ICT and LE features, respectively, so a certain degree of SOC was induced between the CT and LE states with different spin multiplicities as well as ππ* features due to the change in the orbital angular momentum. 17,66–68 A relatively large SOC matrix element of the compound was favorable for its excellent ultralong afterglow in the doped films. As shown in Fig.…”