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.

Figure 1. Nanostructured organosilicon luminophores (NOLs).

(a), Schematic representation of NOLs. (b), Schematic representation of the main synthetic steps for the preparation of NOLs. (c), Chemical structures of NOLs prepared and investigated in this work.

Figure 2. Optical properties of NOLs in dilute THF solutions.

(a), Spectral distributions of absorption cross-sections (C = 10⁻⁵ M). (b), Luminescence spectra (C = 10⁻⁶ M).

Figure 3. Schematic representation of plastic scintillators, their scintillation and amplitude spectra.

(a), Standard plastic scintillator based on PS matrix with activator and spectral shifter luminophores. (b), Plastic scintillator with NOLs combining both activators and spectral shifter in one nanostructure. Energy transfer steps from the excited PS matrix to the activator and form the activator to the spectral shifters are shown with corresponding arrows. (c), Scintillation spectra of a few model PS scintillators (standard Sc0 and with NOL-X – NScX) having different wavelengths of the maximum, the values of which are indicated for each sample. (d), Amplitude spectra, obtained under irradiation of the samples of PS scintillators NScX, containing each 0.01–0.015 M of NOL-X, and the standard scintillator Sc0 with α-particles having the energy of 5.49 MeV.

Figure 4. Amplitude spectra and scintillation decay times of different PS scintillators.

(a), Amplitude spectra, obtained under irradiation of the samples of PS scintillator NSc1b, containing 0.03 M of NOL-1, and the standard scintillator Sc0 with α-particles having the energy of 5.49 MeV. (b), Comparison of the scintillation decay times of the PS scintillator with 0.03 M of NOL-1 (NSc1b) and the standard PS scintillator Sc0.