8 research outputs found
Novel Triazine-Based DonorAcceptor Ionic Green Emitters for Nondoped Light-Emitting Electrochemical Cells
Phenanthroimidazole Derivative as an Easily Accessible Emitter for Non-Doped Light-Emitting Electrochemical Cells
We report a versatile approach to
harvest electroluminescence from
a nondoped light-emitting electrochemical cell (LEC) using an easily
accessible phenanthroimidazole derivative. The authors investigated
two different types, (i) ionic and (ii) neutral phenanthroimidazole
derivatives by modifying our previously reported LEC emitter. Sky-blue
electroluminescence was achieved by applying these modified emitter
in LEC devices. In comparison to the parent molecule, a highly contrasting
performance was exhibited by all the modified emitters except the
neutral butyl derivative (nbpypn). By employing an ionic molecule
(ihpypn) in a fully solution-processed typical LEC device structure,
a peak brightness of 711 cd/m<sup>2</sup> was observed at a current
efficiency of 0.18 cd/A. Our champion device (ihpypn-LEC) presented
a 5-fold increase in maximum brightness at a ten times higher current
density than its parent molecule. These peak brightness values are
among the best comparing to those reported for LECs with the corresponding
emission colors. Even though the neutral molecules did not show any
high electroluminescence, their current efficiency at maximum brightness
has improved 20 times when compared to its parent molecule utilized
device. The study reveals that substituents on imidazole nitrogen
has a critical impact on its performance in the LEC devices. This
result is even more encouraging, considering that our molecular design
can be applied to the majority of the imidazole derivatives and may
open-up a plausible way of enriching the library of emitters for LECs
with efficient and easily obtainable small organic molecules
Green Electroluminescence from Charged Phenothiazine Derivative
A novel
charged green-emitting organic small molecule, PPP, was
synthesized and characterized by thermal, photophysical, electrochemical,
and electroluminescence investigations. The theoretical properties
of PPP were confirmed by means of computational studies. PPP exhibits
a good thermal decomposition temperature of 355 °C. The compound
PPP shows positive solvatochromism upon increasing the solvent polarity
due to the more polarized excited state arising from the intramolecular
charge transfer in the excited state. Solid-state emission of PPP
was slightly red-shifted compared to that of its solution emission
spectrum, showing the reduced intermolecular interaction in the solid
state. Solution-processed LEC devices were fabricated using PPP as
a neat light-emitting layer. The fabricated single-component light-emitting
electrochemical cell devices exhibited green electroluminescence centered
at 530 nm with the CIE coordinates of (0.32, 0.58). Electroluminescent
devices operated at very low turn-on voltages reveal a maximum luminance
of 499 cd/m<sup>2</sup>. These promising results are highly desirable
for the development of low-cost lighting devices
Merging supramolecular catalysis and aminocatalysis: amino-appended β-cyclodextrins (ACDs) as efficient and recyclable supramolecular catalysts for the synthesis of tetraketones
Introduction of heterocyclic ring to phenanthroimidazole moiety for efficient blue emitting ionic small molecule LECs
Eleven tips for operational researchers working with health programmes: our experience based on implementing differentiated tuberculosis care in south India
Due to the workload and lack of a critical mass of trained operational researchers within their ranks, health systems and programmes may not be able to dedicate sufficient time to conducting operational research (OR). Hence, they may need the technical support of operational researchers from research/academic organisations. Additionally, there is a knowledge gap regarding implementing differentiated tuberculosis (TB) care in programme settings. In this ‘how we did it’ paper, we share our experience of implementing a differentiated TB care model along with an inbuilt OR component in Tamil Nadu, a southern state in India. This was a health system initiative through a collaboration of the State TB cell with the Indian Council of Medical Research institutes and the World Health Organisation country office in India. The learnings are in the form of eleven tips: four broad principles (OR on priority areas and make it a health system initiative, implement simple and holistic ideas, embed OR within routine programme settings, aim for long-term engagement), four related to strategic planning (big team of investigators, joint leadership, decentralised decision-making, working in advance) and three about implementation planning (conducting pilots, smart use of e-tools and operational research publications at frequent intervals). These may act as a guide for other Indian states, high TB burden countries that want to implement differentiated care, and for operational researchers in providing technical assistance for strengthening implementation and conducting OR in health systems and programmes (TB or other health programmes). Following these tips may increase the chances of i) an enriching engagement, ii) policy/practice change, and iii) sustainable implementation