Theoretical study of charge-transport and optical properties of indeno[1,2-b]fluorene-6,12-dione-based semiconducting materials

Abstract

The conducting and optical properties of a series of indeno [1,2-b]fluorene-6,12dione (IFD)-based molecules have been systematically studied and the influences of butyl, butylthio and dibutylamino substituents on the reorganization energies, intermolecular electronic couplings and charge-injection barriers of IFD have been discussed. The quantum-chemical calculations combined with electron-transfer theory reveal that the incorporation of sulfur-linked side chains decreases reorganization energy associated with hole transfer and optimizes intermolecularstacking, which results in excellent ambipolar charge-transport properties ( h = 1.15 cm 2 V À1 s À1 and e = 0.08 cm 2 V À1 s À1 ); in comparison, addition of dibutylamino side chains increases intermolecular steric interactions and hinders perfect intermolecularstacking, which results in the weak electronic couplings and finally causes the low intrinsic hole mobility ( h = 0.01 cm 2 V À1 s À1 ). Furthermore, electronic spectra of butyl-IFD, butylthio-IFD and dibutylamino-IFD were simulated and compared with the reported experimental data. Calculations demonstrate that IFD-based molecules possess potential for developing novel infrared and near-infrared probe materials via suitable chemical modifications. research papers Acta Cryst. (2018). B74, 705-711 Jin-Dou Huang et al. IFD-based semiconducting materials 711

Theoretical insights into excited-state hydrogen bonding effects and intramolecular proton transfer (ESIPT) mechanism for BTS system

“…It indicates that the net electron densities shift from hydroxyl groups to atoms N3 and N6 upon photoexcitation of BTS from state S 0 to state S 1 . Particularly, the CDD figure reveals more obvious charge redistributions via hydrogen bond O1-H2···N3, which provides the tendency for ESIPT reaction [26][27][28][29][30][31][32][33][34][35] . Therefore, we can infer that hydrogen bond O1-H2···N3 should play a more important role during the ESIPT process of BTS.…”

“…Constructing and analyzing potential energy curves should be an efficient manner to explore the ESIPT mechanism [26][27][28][29][30][31][32][33][34][35] . For BTS system, we could firstly exclude the excited-state double proton transfer process since the BTS-PT3 structure owns the highest energy (seen in Fig.…”

“…By the light of nature, both applied and cognitive attention have been paid to ESIPT phenomenon, which becomes a demanding subject of research [19][20][21][22][23][24][25] .Generally, ESIPT means the transfer of a hydroxyl (or amino) proton to an oxygen (or nitrogen) acceptor via pre-existing hydrogen bonds. Upon photoexcitation, an unstable position of proton is resulted from the projection of the nuclear wave function of molecule on the excited-state potential energy surface (PES) [26][27][28][29][30][31][32][33][34][35] . The driving force for ESIPT is provided by the energy gap between the initial and relaxed excited states.…”

“…Demonstrating by the mirror symmetry between absorption and emission spectra, the nuclear configuration of the target molecule remains close to that of the ground state over the excited-state lifetime. The mirror symmetry should be broken up by the influence of ESIPT on the Franck-Condon factors [26][27][28][29][30][31][32][33][34][35] . The proton-transfer tautomer emits fluorescence at longer wavelength and results in larger Stokes shifts.As far as we know, single ESPT process may not be sufficient to investigate the complex hydrogen bonding behaviors in biological fields, since more and more photo-induced mutations refer to multiple protons [36][37][38][39] .…”

Revealing and comparing different excited‐state intramolecular proton transfer processes for 3‐(4‐dimethylamino‐phenyl)‐1‐(4‐fluoro‐2‐hydroxy‐phenyl)‐propenone and 3‐(4‐dimethylamino‐phenyl)‐1‐(4‐fluoro‐2‐hydroxy‐phenyl)‐3‐hydroxy‐propenon

“…[32] In effect, for these two similar M1 and M2 structures, it should be better to make a comparative investigation about excited-state dynamical behaviors, since different structures do result in different possible processes. [33][34][35][36][37][38][39][40][41][42][43] Moreover, previous experimental reports do not focus on clarifying excited-state mechanism for both M1 and M2 systems. We believe that investigations about clarifying the ESIPT mechanisms of M1 and M2 could be useful for further understanding their characteristics for reasonable applications.…”