Theoretical studies of the effect of electron-withdrawing dicyanovinyl group on the electronic and charge-transport properties of fluorene-thiophene oligomers

Abstract

At the quantum-chemical level, we characterize some important parameters that control photoelectronic properties of three p-conjugated fluorene-thiophene oligomers namely, 2,7-di(2-thienyl)-9,9-dihexylfluorene, 2,5-Bis-(9H-fluorene-2-yl)-thieno[3,2-b]thiophene and 2,7-Bis [5-(1,1-dicyanovinyl)thiophene-2-yl]-9,9-di-n-hexylfluorene (FTCN). The geometric and electronic structures of these compounds in the ground and the lowest singlet excited states were studied using density function theory. By employing the incoherent transport model, the electron and hole mobilities were evaluated on a wide variety of nearest-neighbor charge transfer pathways. These results show that the chemical modifications by changing linkage mode or introducing the electron-withdrawing group could improve the charge transfer, especially for FTCN. Meanwhile, it is found that the packing effect weakens the emission intensity to some extent according to the simulations of photoluminescences of dimers.

Molecular stacking character and charge transport properties of tetrabenzoheptacenes derivatives: the effects of nitrogen doping and phenyl substitution

“…The model has been adopted in previous theoretical works [26][27][28]. For each hopping event, the charge transfer rate for self-exchange charge transfer processes (the Marcus theory driving force is negligible) can be expressed by the following equation [29][30][31]:…”

Deep‐Blue Thiophene‐Based Steric Oligomers as a Low‐Threshold Laser Gain and Host Material

“…Particularly, Th and their derivatives have emerged with potential applications in organic optoelectronic devices because of their interesting optical and electrical properties as well as chemical stability. [ 14,23,27–35 ] Oligothiophenes and polythiophenes are of considerable interest, thanks to their excellent self‐assembly behavior that could induce oriented and packed arrangement in a condensed structure toward improving charge transport ability, which is a potential candidate for light‐emitting devices. [ 36,37 ] However, reports about Th derivatives as gain media are rare and the performance is poor, especially for the deep‐blue emission.…”

“…[ 28,34,48,49 ] Meanwhile, as a typical conjugated segment, combining fluorene and Th units is the fact that fluorene segment shows intrinsic high luminescence efficiency in the blue spectral region. [ 2,32,50,51 ] However, there are rare efficient Th‐based deep‐blue fluorophores explored as gain materials for organic laser. [ 13 ] Herein, we synthesized a novel Th‐based blue fluorescent steric molecule MC8‐Th with exceptional amplified spontaneous emission (ASE) behavior for deep‐blue organic lasers ( Scheme a).…”

“…[ 52,53 ] It is believed that the steric unit at 9‐postion will partial suppress intermolecular aggregation at molecular level and precisely tune molecular self‐crystallization behavior. [ 13,18,30,32 ] Although it presents low PLQY value (8.8%), the spin‐coated neat film exhibits exceptional deep‐blue ASE behavior with a remarkably low threshold of 6.0 µJ cm −2 and full‐width‐at‐half‐maximum (FWHM) value of 2.6 nm under vacuum atmosphere. By means of incorporating the compound into an inert polystyrene (PS) matrix with various doping proportions, intermolecular interactions were effectively suppressed, and random lasing behavior were observed (under vacuum condition) with the lowest threshold of 4.1 µJ cm −2 .…”

Influence of push–pull configuration on the electro-optical and charge transport properties of novel naphtho-difuran derivatives: a DFT study

“…[23][24][25][26][27][28] Several experimental and theoretical research reports are available on thiophene containing materials for use in OFETs and OLEDs. [29][30][31][32][33][34][35][36][37][38] The push-pull effect on the electronic, optical and charge transport properties of the benzo [2,3-b]thiophene derivatives has been studied theoretically. 6 However, in the literature only a very small number of investigations has been reported about the furan containing OFETs and OLEDs materials.…”