Effect of end group functionalisation of small molecules featuring the fluorene–thiophene–benzothiadiazole motif as emitters in solution-processed red and orange organic light-emitting diodes

Abstract

A series of red fluorescent materials (compounds 1-4), which each contain the symmetric fluorene-thiophene-BT-thiophene-fluorene core, is presented along with their performance in solution-processed OLED devices.Extending the molecular conjugation through end-capping with additional fluorene units (compound 2), or through incorporation of donor functionalities (compounds 3 and 4) improves OLED performance relative to the parent compound 1. Notably, incorporating triphenylamine donor groups in compound 3 led to solutionprocessed OLED devices operating with a peak luminance of 2888 cd m À2 and a low turn-on voltage (3.6 V). † Electronic supplementary information (ESI) available: The graphs for the oxidation and reduction CV cycles of compounds 1-4 are shown in the ESI in Fig. S1-S4, as well as the optical microscope images in Fig. S5, AFM images of unannealed films and films annealed at 80 1C in Fig. S6 and S7 respectively, OLED data at various annealing temperatures of compound 1-4 in Table S1 and 1 H and 13 C NMR spectra for compounds 1-4 in Fig. S8-S15. Supporting data are accessible from http://dx.doi. a Recorded as an average over 8 devices. b Recorded as an average over 4 devices. c Recorded as an average over 6 devices. d Recorded as an average over 3 devices. The best turn on voltages of each compound was recorded without using Alq 3 .

A Study on Varying the Number of Fluorene Units in 2, 1, 3‐Benzothiadiazole‐Containing Oligomers and the Effect on OLED Performance and Stability

“…In this work, we explore the performance of larger oligofluorene analogues to see how the molecular size affects device performance. Previous reports of fluorene‐containing small molecules or oligomers have shown that the number of fluorene groups can influence OLED characteristics such as maximum luminance, efficiency and roll‐off, and turn‐on voltage [5b,11] . In this study, we show that the length of the arms attached influences the luminance, efficiency and lifetime of the OLED devices.…”

Highly emissive supramolecular gold(i)–BTD materials

“…On the other hand, the flat topology of this moiety together with the presence of chalcogen and nitrogen atoms in its structure confers this moiety a strong tendency to establish cooperative intermolecular interactions such as chalcogen bonding and π–π stacking. Thanks to their impressive optical properties BTD derivatives have been widely used as components in the fabrication of organic light-emitting diodes (OLEDs), 12 organic solar cells (OSCs), 13 bioimaging, 14 fluorescence sensing, 15 and stimuli-responsive fluorophores, 16,17 and fluorescent lysosome-staining agents 18 among others.…”

Effect of structural modifications on the spectral and lasing characteristics of truxene-cored starbursts with/without diphenylamine end-cappers

“…According to the results, the lasing wavelength of Tr3D showed 27 nm redshifts compared with Tr3, which was in accordance with the trend of the PL and ASE spectra. This end-capping strategy [58,59] has great potential for developing high-efficiency organic laser materials for optoelectronics, and it may offer renewed hope for high-performance organic lasing.…”