Growth of Pentacene-Doped p-Terphenyl Crystals by Vertical Bridgman Technique and Doping Effect on Their Characterization

Abstract

High quality pentacene-doped p-terphenyl crystals were successfully grown by the modified vertical Bridgman technique with a specially designed double-walled ampule. Upon the dopant addition, the growth crystal exhibits a color change from colorless to purple due to the guest-induced absorption changes. Powder X-ray diffraction, Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR), and fluorescence spectra studies of the doped crystal were carried out and compared with those of a pure p-terphenyl crystal. The decrease in both crystallinity and fluorescent intensity of the doped crystal clearly indicates that the guest molecules appear as defects in the form of irregularly oriented molecules which do not significantly distort the crystal structures. No significant changes on FTIR and 1H NMR spectral features of the doped crystal in relation to the corresponding features observed for the single crystal shows that the crystal doping in such small amounts does not lead to noticeable changes of the intermolecular interaction energy.

Growth Regulation of Pentacene-Doped p-Terphenyl Crystals on Their Physical Properties for Promising Maser Gain Medium

“…A small disparity in the relative intensities of the diffraction peaks is owing to the discrepancy in statistical orientations of the powder grains fabricated from the as-grown bulk crystals. Both the crystals belong to the monoclinic space group of P 2 1 / a , in agreement with the reported structure . The X-ray diffractions were also conducted on the cleavage wafers.…”

“…Many well-established methods used for inorganic crystal growth can be modified for growth of organic single crystals, whereas the relative weak van der Waals bonds between molecules, the large dimensions of molecular growth units, and the low thermal stability of organic materials impose specific limitations on the use of these techniques. Pentacenedoped p-terphenyl crystals could be grown by both the Bridgman method 20 and cosublimation of the mixed or separated materials. 13 Because applications such as scintillation detectors and optically pumped masers require large crystals of a few cubic centimeters in size, only the melt growth techniques are sufficient.…”

Facile synthesis of potassium intercalated p-terphenyl and signatures of a possible high Tc phase

“…In Figure 2 Structural identification of p-terphenyl flakes was carried out using the FTIR spectroscopy (Figure 2). This optical transmission spectrum of p-terphenyl matches well with the single crystal FTIR spectrum of p-terphenyl reported earlier [19]. Prominent peaks at 658.6 and 744.8 cm -1 belongs to terminal rings C-H bending vibrations while terminal ring C-H bending mode is reflected at 837.8 cm -1 .…”

Pentacene in 1,3,5-Tri(1-naphtyl)benzene: A Novel Standard for Transient EPR Spectroscopy at Room Temperature

“…Below this limit, pentacene molecules randomly replace p-terphenyl molecules with the long axis of the pentacene parallel to the long axis of the displaced host molecule [20,21]. For crystal growth either co-sublimation [20,23] or the Bridgman method is widely used [1,12]. Both methods require specialist equipment which means that samples of p-terphenyl doped with pentacene cannot be prepared in many laboratories.…”