2,5‐Functionalized Spiro‐Bisiloles as Highly Efficient Yellow‐Light Emitters in Electroluminescent Devices

Abstract

New spiro‐bisilole molecules functionalized with nitrogen‐containing heterocyclic groups including 7‐azaindolyl, indolyl, and 2,2′‐dipyridylamino have been synthesized. These molecules are found to display good chemical and thermal stability. They are luminescent in solution and in the solid state with an emission color ranging from blue–green to yellow, depending on the functional group. In the solid state, they display high photoluminescence quantum efficiency (32–40 %). The electroluminescence properties for one of the new molecules, 2,3,3′,4,4′,5‐hexaphenyl‐2′,5′‐bis(p‐2,2′‐dipyridylaminophenyl)spiro‐bisilole, have been investigated by fabricating single‐layer and double‐layer electroluminescent devices. The double‐layer device, in which N,N′‐bis(1‐naphthyl)‐N,N′‐diphenylbenzidine acts as the hole‐transport layer and the functionalized spiro‐bisilole functions as the emitter (emission wavelength = 566 nm) and the electron‐transport layer, displays a brightness of 8440 cd m–2 at 9 V with a current efficiency of 1.71 cd A–1. No evidence of exiplex emission is observed.

Creation of Bifunctional Materials: Improve Electron‐Transporting Ability of Light Emitters Based on AIE‐Active 2,3,4,5‐Tetraphenylsiloles

“…5.4 V), and the peak EL efficiencies are enhanced obviously ( η C , 13.9 vs 8.4 cd A −1 ; η ext , 4.35 vs 2.62%; η P , 11.6 vs 4.1 lm W −1 ) (Table and Supporting Information Figure S3). These values are much better than those obtained from double‐layer OLEDs of the reported n‐type light emitters with close emission colors, such as copolymers of silafluorene and 2,1,3‐benzothiadiazole (10.6 cd A −1 ; 3.81%), folded tetraphenylethene derivatives (7.9 cd A −1 ; 3.1%),[5b] dimesitylboryl‐functionalized tetraphenylethene (7.13 cd A −1 ; 2.7%), cyano‐substituted pyridine derivatives (5.4 cd A −1 ), Alq 3 (3.3 cd A −1 ), spiro‐bisilole derivatives (1.98 cd A −1 ), and so forth.…”

A Theoretical Investigation of Novel Sila- and Germa-Spirocyclic Imines and Their Relevance for Electron-Transporting Materials and Drug Discovery

“…(VI) 1,5,7,10,14,16-hexaimino-3,12-disilsa-6,9-disilaspiro [5.2.59.26]hexadecane (HIDSSCNCH-26). (VII) 2,4,8,10,14,15-hexaimino-3,12-disila-6,9-disilaspiro [5.2.59.26] 16,20,22,26,28,32,34,37,38,41,42,45,46,49 2,4,8,10-tetraimino-3,9-disila-6-silaspiro [5.5]undecane (consisting of 19 atoms) is abbreviated as TISSNU-19.…”

“…However, as far as the author knows, no molecular systems, like the novel silaspirocyclic silaimines (SSCSIs) and germa-spirocyclic germaimines (GSCGIs), have been studied so far. Moreover, this unique cross-hyperconjugative spirocyclic class of compounds with their quasi-rigid linear arrangement and alternating electrophilic and nucleophilic (acceptor-donor) centers could be considered as potential building blocks for intra-molecular charge transfer functional conductive and semiconductive materials (perhaps it is best to designate then as "spiro-metallo-organic semiconductors (SMOSC)") and make them applicable, e.g., for solar cells, optoelectronics, etc., like other related charges transfer spirocyclic molecular systems [38][39][40][41][42]).…”

n‐Type Organic Semiconductors in Organic Electronics

“…OLEDs have been fabricated using siloles as emissive or ET layers 12–17. Tamao et al pioneered the use of siloles as the ET layer in OLEDs; a three‐layer device with the configuration Ag:Mg/ 1c /Alq 3 /TPD/ITO was fabricated using silole 1c , Alq 3 , and N , N ′‐diphenyl‐ N , N ′‐bis(3‐methylphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (TPD) as ET, emissive, and hole transport layer, respectively, with an efficiency of 1.9 lm W −1 12.…”