The inspiration and challenge for through-space charge transfer architecture: from thermally activated delayed fluorescence to non-linear optical properties

Abstract

Organic molecules consisting of electron donor (D) and electron acceptor (A) subunits linked by π-conjugated bridge are promising building blocks for the thermally activated delayed fluorescence (TADF) and nonlinear optical...

An intramolecular-locked strategy for designing nonlinear optical materials with remarkable first hyperpolarizability

“…Different strategies 4,[6][7][8][9][10][11] have been successively proposed to enhance the first hyperpolarizability. Among those strategies, the strategy of designing D-A and Dp-A organic molecules has become a quite important strategy in enhancing the first hyperpolarizability, 4,[11][12][13][14][15][16] mainly owing to the D-A and D-p-A organic molecules holding strong inter(intra)molecular charge transfer (ICT) and having highly delocalized p-electron characteristics. The organic molecules, on the other hand, have also a lower laser damage threshold and easy modification characteristics.…”

First Hyperpolarizabilities of Intramolecular Charge-Transfer Architectures Based on Acenaphthene Derivatives in Gas, Solution, and Solid States

“…10,11 However, the strong TBCT effect of the π-conjugate system will lead to the contradiction between nonlinearity and transparency trade-off, which is not conducive to practical application. 12 Therefore, the development of new methods to balance CT intensity is essential for the structural design and performance optimization of new NLO materials. Through-space CT (TSCT), one of the most significant properties of π electron delocalization, connects D and A units by an electronically benign spacer but remains in close proximity to each other to effectively avoid the negative effects of strong CT.…”

“…18 In our previous work, the correlation advances in the fields of NLO and thermally activated delayed fluorescence (TADF) materials based on TBCT and TSCT characteristics have been introduced, especially for TSCT characteristic. 8,12,19 Recently, Monkman and co-workers reported several compounds (TPA-ace, 2TPA-ace, TPA-ace-CN, and TPAace-TRZ) using acenaphthene as a scaffold and triphenylamine (TPA) as the donor by experimental demonstration and theoretical calculation. 20 Among them, the TPA-ace-TRZ compound with TSCT interaction disposed in a pseudocofacial orientation and linked via a bridging group shows an unexpected and outstanding TADF performance.…”

“…As mentioned in recent review by our research group, the diversity and potential advantages of TSCT characteristic molecules will exhibit the high-performance NLO materials. 12 By all appearances, it is necessary to study the relationship between structure and the second-order NLO property of these novel compounds from the standpoint of the microscopic electronic structure level, which expands its applications and elevates performance. In addition, from the above analysis, the four derivatives based on the TPA unit might provide some new chances for second-order NLO materials because of their inherent asymmetric electronic structures and the delocalized π-electron characters.…”

“…In recent years, most of the CT characteristics of the D–B–A system are based on the through-bond CT (TBCT), which is mainly through the double bond, triple bond, heteroatoms, or aromatic rings to form the π-conjugate structures. It enables strong electron coupling between D and A through covalent bonds. , However, the strong TBCT effect of the π-conjugate system will lead to the contradiction between nonlinearity and transparency trade-off, which is not conducive to practical application . Therefore, the development of new methods to balance CT intensity is essential for the structural design and performance optimization of new NLO materials.…”