Novel Spectrally Stable Saturated Blue‐Light‐Emitting Poly[(fluorene)‐co‐(dioctyldibenzothiophene‐S,S‐dioxide)]s

Abstract

Novel poly[(fluorene)-co-(2,8-dioctyldibenzothiophene-S,S-dioxide-3,7-diyl)]s were synthesized. The octyl group on the 2,8-dioctyldibenzothiophene-S,S-dioxide (DOSO) unit improved the solubility of the polymers and broadened the optical band gap from 2.95 to 3.20 eV as the content of DOSO unit increases. The electroluminescence (EL) spectra of polymers show CIE coordinates around (0.16, 0.07) independent of the ratio of DOSO units in the polymers, owing to the ICT and steric hindrance dual-function. A high efficiency of 3.1 cd · A(-1) (EQE = 3.9%) was obtained with the configuration of ITO/PEDOT:PSS/polymer/Ba/Al. The results indicate that PF-3,7DOSOs could be a promising candidate for saturated blue-emitting polymers with spectral stability and high efficiency.

Efficient Deep‐Blue Electroluminescence Based on Phenanthroimidazole‐Dibenzothiophene Derivatives with Different Oxidation States of the Sulfur Atom

“…[20] In addition, the rigid PI plane can reduce nonradiative vibrational andr otational processes, leading to ah igh PLQY.W hat's more,t he different bonding mode of the two nitrogen atoms in the imidazole ring endows PI with bipolar character. [26] For example, Perepichka et al introduced DBTSO into oligofluorene and obtaineds table and efficient blue emission with improved electron affini-ty. [22] By linking two PI in differentm odes,e fficient blue emission can be expected.…”

“…This positive result inspires us to further develop other analogst oo btain efficient deepblue OLEDs.W en otet hat dibenzothiophene S,S-dioxide (DBTSO) as an acceptor constitutes many efficient blue-emittingD -A polymers and small molecules. [26] For example, Perepichka et al introduced DBTSO into oligofluorene and obtaineds table and efficient blue emission with improved electron affini-ty. [26a] However,t he color purity of many DBTSO-based D-A materials cannots atisfyt he NTSC deep-blue standard.…”

Fluorene co-polymers with high efficiency deep-blue electroluminescence

“…11 A major challenge for the rational design of such systems is that for blue emission the electronic conjugation along the polymer chain must be confined to short segments, but without completely destroying the polymer's charge carrier transport capabilities. In previous work, we 12,13 and others 14 have attached bulky side chains to induce a twist into the polymer backbone and thereby isolate minimal conjugated segments. Nevertheless, in order to push the emission further into the blue (below  max 450 nm) alternative strategies are required.…”

Green‐Light‐Emitting Poly(Spirobifluorene)s with an Electron‐Rich Unit in the Side Chain and an Electron‐Deficient Unit in the Main Chain

“…As shown in Scheme 1 , four electron-donating octyl oxy chains are introduced to the pendant fl uorene unit of PSFs to make the fl uorene unit electron-rich. On the other hand, the electron-defi cient dibenzothiophene-S,Sdioxide ( SO ) unit [19][20][21][22][23][24][25][26] is incorporated into the main chain of PSFs. The resulting polymers exhibit green photoluminescence (PL) and electroluminscence (EL) owing to charge transfer from the tetra-octyloxyfl uorene unit to the SO unit.…”