step-step-guide-for-harnessing-organic-light-emitting-diodes-solution

Step-by-Step Guide for Harnessing Organic Light Emitting Diodes by Solution Processed Device Fabrication of a TADF Emitter

The demand for energy-efficient light sources has witnessed a significant surge in the recent era, due to the increasing awareness towards environmental ...

Indian Institute of Science

In December 2019, a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak occurred and caused the coronavirus disease of 2019 (COVID-19), which affected ~ 190 countries. The World Health Organization (WHO) has declared COVID-19 a pandemic on 11 March 2020.

Novel corona virus (COVID-19) pandemic: current status and possible strategies for detection and treatment of the disease.

We report highly efficient, ultrathin non-doped green and bluish-green organic light-emitting diodes (OLEDs) using a thermally activated delayed fluorescence (TADF) emitter. The green OLED with an ultrathin (∼1 nm) EML showed a 2.6-fold higher external quantum efficiency (EQE) of 13.5% with a luminance of 17 250 cd m than the conventional (30 nm) non-doped device.

Ultrathin non-doped thermally activated delayed fluorescence emitting layer for highly efficient OLEDs.

Metal-free organic emitters with thermally activated delayed fluorescence (TADF) characteristics are emerging due to the potential applications in optoelectronic devices, time-resolved luminescence imaging, and solid-phase sensing. Herein, we synthesized two (4-bromobenzoyl)pyridine (BPy)-based donor-acceptor (D-A) compounds with varying donor size and strength: the emitter BPy-TC with -butylcarbazole (TC) as the donor and BPy-3C with bulky tricarbazole (3C) as the donor unit. Both BPy-TC and BPy-3C exhibited prominent emission with TADF properties in solution and in the solid phase. The stronger excited-state charge transfer was obtained for BPy-3C due to the bulkier donor, leading to a more twisted D-A geometry than that of BPy-TC. Hence, BPy-3C exhibited aggregation-induced enhanced emission (AIEE) in a THF/water mixture. Interestingly, the singlet-triplet energy gap (Δ ) was reduced for both compounds in the aggregated state as compared to toluene solution. Consequently, a faster reverse intersystem crossing rate ( ) was obtained in the aggregated state, facilitating photon upconversion, leading to enhanced delayed fluorescence. Further, the lone-pair electrons of the pyridinyl nitrogen atom were found to be sensitive to acidic protons. Hence, the exposure to acid and base vapors using trifluoroacetic acid (TFA) and triethylamine (TEA) led to solid-phase fluorescence switching with fatigue resistance. The current study demonstrates the role of the donor strength and size in tuning Δ  in the aggregated state as well as the relevance for fluorescence-based acid-base sensing.

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation.

We describe a metal-free strategy to access various α-arylidene cyclopenta[]indoles  phosphine-catalysed (3 + 2) annulation of α,β-ynones and 3-nitroindoles. For the first time, the rearomatisation of the indole nucleus was observed in such an annulative transformation. The method was extended to the synthesis of an antimalarial natural product, bruceolline E.

Phosphine-catalysed denitrative rearomatising (3 + 2) annulation of α,β-ynones and 3-nitroindoles.

The considerable loss of crop productivity each year due to plant disease or pathogen invasion during pre- or post-harvest storage conditions is one of the most severe challenges to achieving the goals of food security for the rising global population. Although chemical pesticides severally affect the food quality and health of consumers, a large population relies on them for plant disease management. But currently, endophytes have been considered one of the most suitable biocontrol agents due to better colonization and acclimatization potential. However, a very limited number of endophytes have been used commercially as biocontrol agents. Isolation of endophytes and their screening to represent potential characteristics as biocontrol agents are considered challenging by different procedures. Through a web search using the keywords "endophytes as biocontrol agents" or "biocontrol mechanism of endophytes," we have succinctly summarised the isolation strategies and different in vitro and in vivo biocontrol screening methods of endophytic biocontrol agents in the present review. In this paper, biocontrol mechanisms of endophytes and their potential application in plant disease management have also been discussed. Furthermore, the registration and regulatory mechanism of the endophytic biocontrol agents are also covered.

Biocontrol Screening of Endophytes: Applications and Limitations.

The development of high-efficiency orange phosphorescent organic light-emitting diodes (PhOLEDs) with reduced efficiency roll-off offers significant benefits, enabling a more simplified method for producing white-OLEDs through the combination of sky blue and orange OLEDs, in contrast to the conventional use of three primary colors. Herein, we have designed and synthesized two hosts with 9-(4-(14H-dibenzo[a,j]xanthen-14-yl)phenyl)-9H-carbazole (XaPCz) and 10-(4-(14H-dibenzo[a,j]xanthen-14-yl)phenyl)acridin-9(10H)-one (XaPAc) derivatives. The singlet and triplet energies for XaPCz and XaPAc are S=3.65, 3.12 eV, and T=2.67, 2.70 eV, respectively. These materials are employed as hosts for orange PhOLEDs using bis(2-phenylquinoline) (acetylacetonate) iridium (III) [Ir(pq)] as an emitter. XaPCz demonstrates maximum external quantum efficiency (EQE) of 20.5 %, and XaPAc shows EQE of 22.3 % with Commission Internationale de l'Eclairage (CIE) coordinates of (0.53, 0.46) and (0.54, 0.45), respectively. In addition, the XaPAc-based device shows a lower turn-on voltage (2.5 V) and high-power efficiency of 60.0 lm/W. More importantly, both device shows reduced roll-off and retain more than 94 % of EQE at 1,000 cd/m. The XaPAc-based device maintains an EQE of 17.9 % even at 10,000 cd/m.

Highly Efficient Orange Phosphorescent Organic Light Emitting Diodes with Reduced Roll-Off Using Xanthene-Conjugated Carbazole and Acridone as Host Materials.

We present the first interrupted Corey-Chaykovsky reaction of α,β-ynones by intercepting the zwitterionic intermediates that prevail during the addition of the Corey-Chaykovsky reagent to activated alkynes. This cascade transformation uncovers a novel mechanistic feature and leverages it to construct complex polycyclic molecular architectures featuring three new carbon-carbon bonds, four new carbo- and heterocycles and four contiguous stereocenters, two of which are quaternary carbons, all in a single-pot operation. Additionally, we demonstrate the synthetic utility of these otherwise unprecedented molecules.

Article	Year
Novel corona virus (COVID-19) pandemic: current status and possible strategies for detection and treatment of the disease. Expert review of anti-infective therapy\| PubMed ID: 33043740	2022
Ultrathin non-doped thermally activated delayed fluorescence emitting layer for highly efficient OLEDs. Chemical communications (Cambridge, England)\| PubMed ID: 34870289	2021
Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation. Beilstein journal of organic chemistry\| PubMed ID: 36128432	2022
Phosphine-catalysed denitrative rearomatising (3 + 2) annulation of α,β-ynones and 3-nitroindoles. Organic & biomolecular chemistry\| PubMed ID: 36601997	2023
Biocontrol Screening of Endophytes: Applications and Limitations. Plants (Basel, Switzerland)\| PubMed ID: 37447041	2023
Highly Efficient Orange Phosphorescent Organic Light Emitting Diodes with Reduced Roll-Off Using Xanthene-Conjugated Carbazole and Acridone as Host Materials. Chemistry, an Asian journal\| PubMed ID: 39988562	2025
Creating skeletal complexity through an interrupted Corey-Chaykovsky reaction of activated alkynes. Chemical communications (Cambridge, England)\| PubMed ID: 40905124	2025

Nisha Yadav

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