High-Performance Organic Light-Emitting Diodes Based on Dioxolane-Substituted Pentacene Derivatives

Abstract

Organic light‐emitting diodes (OLEDs) containing red‐light‐emitting dioxolane‐substituted pentacene derivatives are fabricated and characterized. The OLEDs feature guest–host emitting layers consisting of either 6,14‐bis(triisopropylsilylethynyl)‐1,3,9,11‐tetraoxa‐dicyclopenta[b,m]pentacene (TP‐5) or 2,2,10,10‐tetraethyl‐6,14‐bis(triisopropylsilylethynyl)‐1,3,9,11‐tetraoxa‐dicyclopenta[b,m]pentacene (EtTP‐5) dispersed in tris(quinolin‐8‐olato) aluminum(III) (Alq3). High external electroluminescence (EL) quantum efficiency (ηEL = 3.3 %), not far from the theoretical limit, is observed for an OLED device based on a dilute EtTP‐5:Alq3 emitting layer (0.25 mol % EtTP‐5). The proposed EL mechanism is a combination of Förster energy transfer and direct electron–hole recombination on the guest pentacene molecules, as inferred by changes in the EL versus photoluminescence spectra and the positions of the highest occupied molecular orbital and lowest unoccupied molecular orbital gap of the guest within that of the host (estimated via cyclic voltammetry). Further evidence of charge trapping is provided by increased operational voltages at increased guest‐molecule concentration.

Conjugated Organosilicon Materials for Organic Electronics and Photonics

“…This compound has an increased chromophore stacking distance in the crystal (5.5 Å vs 3.4 Å for TIPS-5AC-DO) and allowed a concentration up to 2% of dopant in both Alq 3 and NPD matrixes without formation of aggregates. OLEDs prepared from such composites showed bright red emission with an external electroluminescence quantum yield of 3.3% [47], close to the theoretical maximum and also very close to the highest value reported (3.6%) [48] for a small-molecule red-emissive OLED.…”

“…In contrast to the random copolymer, the alternating copolymer exhibited a broad absorption band which obviously results from the mixed configuration dominated by the TST segment. In films with a low 47 Structural formulas of (a) 9,9-dioctylfluorene (FO) and 1,1-dimethyl-3,4-diphenyl-2,5-bis(2 -thienyl)silole (TST) copolymers PFO-TST [218] and (b) N-hexyl-3,6-carbazole (Cz) and 1,1-dimethyl-2,3,4,5-tetraphenylsilole (PSP) copolymers PCz-PSP [219] TST content the excitation energy completely transferred from the PFO to the TST segment. In OLEDs (layer structure ITO/PEDOT/PVK/copolymer/Ba/Al) the emitted light from the copolymers was found to be red-shifted.…”

Höhere Acene: vielseitige organische Halbleiter

“…Auch einige stabile Pentacenether sind bekannt, deren Oxidationspotentiale noch geringer sind (z. T. nur 560 mV gegen SCE; Abbildung 26). [312] Das Dioxolan-Pentacen 69 weist interessante [314] und der Bestmarke von 3.6 % [315] für rote Leuchtdioden mit niedermolekularen organischen Verbindungen.…”

Acridine-Triphenylamine Based Hole-Transporting and Hole-Injecting Material for Highly Efficient Phosphorescent-Based Organic Light Emitting Diodes

“…There is a hole-injecting layer (HIL), hole-transporting layer (HTL), emission layer (EML), electron-transporting layer (ETL), electron-injecting layer (EIL) embedded between two electrodes, the anode and cathode, which is known as a multilayer OLED structure. Multilayer OLED devices have improved the quantum efficiency when compared to single-layer devices [1][2][3][4]. Hole-transporting materials (HTM) play a major role to transporting holes from the anode to the emission layer and providing charge balance to prevent efficiency roll-off, since the hole transportation process faces critical issues, like thermal MA, USA) operating at 500 MHz.…”