Design of Deep Blue Electroluminescent Spiro-Polyfluorenes with High Efficiency by Facilitating the Injection of Charge Carriers through Incorporation of Multiple Charge Transport Moieties

For polymer light-emitting diodes, developing highly efficient, stable, and saturated blue emitting polymer is essential in display and lighting applications and has long been a challenge. Here we report a concept for designing highly efficient electroluminescent polymers by introducing multiple charge transport moieties for efficient injection of charge carriers into spiro-polyfluorene (sPF). We integrate the triphenylamine (TPA) and carbazole (Cz) in the same side chain of sPF with logical spatial and energetic sequence of these moieties to establish graded route for more efficient hole injection and incorporate the electron transport moiety with strong electron-withdrawing capability, triazole (TAZ), on both chain ends to give favorable arrangement in space and energy for electron injection. These two factors allow the corresponding single layer device to exhibit deep blue (db) emission with external quantum efficiency (η_ext) of 7.28%, which is the highest value among the db polymer fluorescent diodes ever documented

Functional outcomes of patients with acute stroke in the presence of ROAF or intracranial stenosis.

<p>Patients with acute stroke were divided into 4 subgroups: severe intracranial stenosis (>50%) and forward OA, severe intracranial stenosis (>50%) and reversed OA, mild intracranial stenosis (≤50%) and forward OA, and mild intracranial stenosis (≤50%) and reversed OA.ROAF and less intracranial stenosis are good predictors for acute stroke outcomes. mRS, modified Rankin Scale; NIHSS, National Institutes of Health Stroke Scale; no., number; OA, ophthalmic artery; <i>*</i>p = p value for trend. Statistically significant differences were evaluated using Fisher's exact test for categorical variables between the tested groups and Mantel–Haenszel extension tests for trend analyses. ^ap<0.05 vs. forward OA and intracranial stenosis >50%; ^bp<0.01 vs. forward OA and intracranial stenosis >50%; ^cp<0.05 vs. reversed OA and intracranial stenosis >50%; ^dp<0.01 vs. reversed OA and intracranial stenosis >50%.</p

Age-adjusted analysis of clinical characteristics in acute strokes with unilateral high-grade cervical internal carotid stenosis or occlusion.

<p>AF, atrial fibrillation; CAD, coronary artery disease; CI, confidence interval; DM, diabetes mellitus; F, female; M, male; NIHSS, National Institutes of Health Stroke Scale; no, number; OA, ophthalmic artery; OR, odds ratio. Statistically significant differences for categorical variables between tested groups were evaluated using age-adjusted logistic analysis.</p

Study patient selection.

<p>FOAF, forward ophthalmic artery flow; MR, magnetic resonance; ROAF, reversed ophthalmic artery flow; EC-IC bypass, extracranial–intracranial bypass.</p

Multivariate analysis of risk factors for acute stroke in patients with unilateral high-grade cervical internal carotid stenosis or occlusion.

<p>CI, confidence interval; DM, diabetes mellitus; no., number; OR, odds ratio; ROAF, reversed ophthalmic artery flow.</p><p>Model 1: Statistically significant difference determined using multivariate logistic regression with forward selection model controlled for age, gender, vascular risk factors, and cervical stenosis but not including the variable of intracranial stenosis.</p><p>Model 2: Statistically significant difference determined using multivariate logistic regression with forward selection model controlled for age, gender, vascular risk factors, cervical stenosis, and ophthalmic artery flow direction.</p