Nanostructured organosilicon luminophores and their application in highly efficient plastic scintillators

Abstract

Organic luminophores are widely used in various optoelectronic devices, which serve for photonics, nuclear and particle physics, quantum electronics, medical diagnostics and many other fields of science and technology. Improving their spectral-luminescent characteristics for particular technical requirements of the devices is a challenging task. Here we show a new concept to universal solution of this problem by creation of nanostructured organosilicon luminophores (NOLs), which are a particular type of dendritic molecular antennas. They combine the best properties of organic luminophores and inorganic quantum dots: high absorption cross-section, excellent photoluminescence quantum yield, fast luminescence decay time and good processability. A NOL consists of two types of covalently bonded via silicon atoms organic luminophores with efficient Förster energy transfer between them. Using NOLs in plastic scintillators, widely utilized for radiation detection and in elementary particles discoveries, led to a breakthrough in their efficiency, which combines both high light output and fast decay time. Moreover, for the first time plastic scintillators, which emit light in the desired wavelength region ranging from 370 to 700 nm, have been created. We anticipate further applications of NOLs as working elements of pulsed dye lasers in photonics, optoelectronics and as fluorescent labels in biology and medical diagnostics.

Nanostructured Organosilicon Luminophores for Effective Light Conversion in Organic Light Emitting Diodes

“…4. Earlier investigation of the optical properties of the organosilicon dendritic molecular antennas have shown that photons in these systems are absorbed by the donor and acceptor chromophores independently of each other and there is no π-conjugation between the chromophores linked through silicon atoms in the molecules [29,30,32]. Therefore, it is not surprising that comparison of the absorption spectra of NOL4 and NOL5 with the corresponding model compounds 1 and 2 indicated that the absorption spectra of these dendritic molecules is a sum of the absorption spectra of the bithiophenesilane (2T) and 1,4-bis(2,2'-bithiophene-5-yl)benzene (2T-Ph-2T) fragments (Fig.…”

“…Solution of this problem has been demonstrated recently by the utilization of oligothiophenephenylene or oligophenylene chromophores having higher luminescence efficiency as compared to oligothiophenes [32,33]. These novel highly luminescent branched molecules were named as "nanostructured organosilicon luminophores" (NOLs) due to the interesting observation that their optical properties combine the best characteristics of organic luminophores and inorganic quantum dots [32].…”

“…Solution of this problem has been demonstrated recently by the utilization of oligothiophenephenylene or oligophenylene chromophores having higher luminescence efficiency as compared to oligothiophenes [32,33]. These novel highly luminescent branched molecules were named as "nanostructured organosilicon luminophores" (NOLs) due to the interesting observation that their optical properties combine the best characteristics of organic luminophores and inorganic quantum dots [32]. In this work, we study the structure-property relationships for two generations of such dendritic molecules, NOL4 and NOL5 (Scheme 1), having 4 or 12 donor 2,2'-bithiophene units, respectively, and the acceptor 1,4-bis(2,2 ′ -bithiophene-5-yl)benzene unit, and demonstrate the possibility to utilize these molecules as efficient wavelength shifters in OLEDs.…”

Influence of chemical structure of branched and dendritic organosilicon luminophores on their optical and thermal properties

“…However, it is also necessary to take into account optical losses (L) related to self-absorption of a particular luminophore because of partial overlap of its absorption and luminescence spectra, a measure of which can be related to the difference between their maxima called as the Stokes shift (S). To solve these problems, we recently suggested the concept of "Nanostructured Organosilicon Luminophores" (NOLs) [17,18], which are a kind of highly efficient dendritic molecular antenna [19,20], consisting of donor and acceptor fragments covalently linked through silicon atoms with very efficient Förster resonance energy transfer (FRET) between them.…”

“…4 , (PTPTP)Si 2 (2T-Hex) 6 and (PTPTP)Si 6 (2T) 4 (2T-Hex) 8 synthesized and investigated in this work. [17], (2,2'-bithien-5-yl)[bis(5'-hexyl-2,2'-bithien-5-yl)]methylsilane 2T-SiMe(2T-Hex) 2 [19] were prepared as reported before. Synthesis of 1,4-bis[5-{4-(trimethylsilyl)phenyl}thiophene-2-yl]benzene (TMS-PTPTP-TMS) and 1,4-bis[5-{4-[tris(5'-hexyl-2,2'-bithien-5-yl)silyl]phenyl}thiophene-2-yl]benzene (PTPTP)Si 2 (2T-Hex) 6 was described elsewhere [26].…”