White Light
Emitting Polymers from a Luminogen with Local Polarity Induced Enhanced
Emission
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Abstract
Aggregation
induced enhanced emission (AIEE) is considered as an important tool
to circumvent the aggregation caused quenching (ACQ) effect in organic
light emitting diodes (OLEDs). Charge trapping and surplus long wavelength
electroluminescence is a cause of concern in single polymer based
white OLEDs. However, the potential of luminogens with AIEE property
as a credible tool to offset the above problems in white light emitting
single polymer is not properly explored. In this study design, synthesis
and spectral characterization of a polymerizable luminogen, (2<i>Z</i>,2′<i>Z</i>)-6,6′-(2,7-dibromo-9<i>H</i>-fluorene-9,9-diyl)bis(hexane-6,1-diyl)bis(2-cyano-3-(10-hexyl-10<i>H</i>-phenothiazin-3-yl)acrylate(FCPA) with AIEE property and
its copolymers is presented. Lippert-Mataga studies showed that reduced
local polarity caused by aliphatic chains in condensed state of FCPA
resulted in AIEE property. The copolymers P(FCPA-1) and P(FCPA-0.5)
with 1% and 0.5% FCPA moieties showed white electroluminescence and
enhanced thin film photoluminescence that matched very closely. The
superior performance of OLEDs is attributed to the presence of a phenothiazine
group in FCPA that resulted in nearly equal electron and hole injection
barriers