Preparation of Organic Light-Emitting Diode Using Coal Tar Pitch, a Low-Cost Material, for Printable Devices

Abstract

We have identified coal tar pitch, a very cheap organic material made from coal during the iron-making process, as a source from which could be obtained emissive molecules for organic light-emitting diodes. Coal tar pitch was separated by simple dissolution in organic solvent, and subsequent separation by preparative thin-layer chromatography was used to obtain emissive organic molecules. The retardation factor of preparative thin-layer chromatography played a major role in deciding the emission characteristics of the solution as photoluminescence spectra and emission-excitation matrix spectra could be controlled by modifying the solution preparation method. In addition, the device characteristics could be improved by modifying the solution preparation method. Two rounds of preparative thin-layer chromatography separation could improve the luminance of organic light-emitting diodes with coal tar pitch, indicating that less polar components are favorable for enhancing the luminance and device performance. By appropriate choice of the solvent, the photoluminescence peak wavelength of separated coal tar pitch could be shifted from 429 nm (cyclohexane) to 550 nm (chloroform), and consequently, the optical properties of the coal tar pitch solution could be easily tuned. Hence, the use of such multicomponent materials is advantageous for fine-tuning the net properties at a low cost. Furthermore, an indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/coal tar pitch/LiF/Al system, in which the emissive layer was formed by spin-coating a tetrahydrofuran solution of coal tar pitch on the substrate, showed a luminance of 176 cd/m2. In addition, the emission spectrum of coal tar pitch was narrowed after the preparative thin-layer chromatography process by removing the excess emissive molecules.

Analyzing solid fossil-fuel pitches by a combination of Soxhlet extraction and Fourier transform ion cyclotron resonance mass spectrometry

“…Based on the molecular composition and structure of each subfraction, a more rational and economically viable utilization can be developed. For example, the bridged archipelago structures (PP-S & CTP-S representative structures in figure 5) can be directly solution-processed or further functionionalized by introducing other chemical moieties for the preparation of organic light-emitting diodes(OLEDs) [54,55]. Although it may remain empirical to predict the electronic transport and other physical properties of the devices which are made from such mixtures, product classification and quality assurance can be achieved by measuring the product performances after manufacturing.…”

NF-E2-related factor 2 serves a key function in resistance to malignant transformation of BEAS-2B cells induced by coal tar pitch

“…Coal tar pitch (CTP) has been determined to be a potent risk factor to human health. This material represents the collective by-products of the combustion of organic materials that are widely used in everyday life (1)(2)(3). Epidemiological studies and animal experiments have demonstrated that CTP is carcinogenic and leads to the development of lung cancer, often considered to be an occupational tumor (4)(5)(6).…”

Determination of Dopamine in the Presence of Ascorbic Acid on Digitonin-Doped Coal Tar Pitch Carbonaceous Electrode

“…They are quite an original research topic in electrochemistry and may be used, for example, as sensor templates, (14) electronic device elements, (15) heat exchangers, (16) and supercapacitors. (17) The CTP is a very low cost material (18) for these studies and an excellent precursor for carbonaceous composites. (19) It has high conductivity and stability, and a large surface area.…”