Influence of Multiple rISC Channels on the Maximum Efficiency and Roll-Off of TADF OLEDs.

In this work, we look into the detailed photophysical characterization of a multidonor-acceptor () family of thermally activated delayed fluorescent (TADF) emitters to find correlations with their device performance. Increasing the number of closely packed s around the core leads to changes in dihedral angles between s and affecting the highest occupied molecular orbital (HOMO)/lowest unpccupied molecualar orbital (LUMO) separation and impacting the singlet-triplet energy gaps. Moreover, dihedral angles change molecular conjugation affecting the spread of charge-transfer state energies as well as the energy of local triplet states.

Influence of Side Chain Interdigitation on Strain and Charge Mobility of Planar Indacenodithiophene Copolymers.

Indacenodithiophene (IDT) copolymers are a class of conjugated polymers that have limited long-range order and high hole mobilities, which makes them promising candidates for use in deformable electronic devices. Key to their high hole mobilities is the coplanar monomer repeat units within the backbone. Poly(indacenodithiophene-benzothiadiazole) (PIDT-BT) and poly(indacenodithiophene-thiapyrollodione) (PIDT-TPD) are two IDT copolymers with planar backbones, but they are brittle at low molecular weight and have unsuitably high elastic moduli.

Ligand Decomposition during Nanoparticle Synthesis: Influence of Ligand Structure and Precursor Selection.

Aliphatic amine and carboxylic acid ligands are widely used as organic solvents during the bottom-up synthesis of inorganic nanoparticles (NPs). Although the ligands' ability to alter final NP properties has been widely studied, side reactivity of these ligands is emerging as an important mechanism to consider. In this work, we study the thermal decomposition of common ligands with varying functional groups (amines and carboxylic acids) and bond saturations (from saturated to polyunsaturated).

Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt?

Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed to─purportedly─rigidify the structure and improve the emission performance of these materials. However, direct evidence for these intramolecular interactions is often lacking or ambiguous, leading to assertions that are largely speculative. Here we investigate a series of TADF-active materials incorporating pyridine, which bestows the potential ability to form intramolecular H-bonding interactions.

Gaining control over conjugated polymer morphology to improve the performance of organic electronics.

Conjugated polymers (CPs) are widely used in various domains of organic electronics. However, the performance of organic electronic devices can be variable due to the lack of precise predictive control over the polymer microstructure. While the chemical structure of CPs is important, CP microstructure also plays an important role in determining the charge-transport, optical and mechanical properties suitable for a target device.

The effect of side chain engineering on conjugated polymers in organic electrochemical transistors for bioelectronic applications.

Bioelectronics focuses on the establishment of the connection between the ion-driven biosystems and readable electronic signals. Organic electrochemical transistors (OECTs) offer a viable solution for this task. Organic mixed ionic/electronic conductors (OMIECs) rest at the heart of OECTs.

Molecular Design Strategies toward Improvement of Charge Injection and Ionic Conduction in Organic Mixed Ionic-Electronic Conductors for Organic Electrochemical Transistors.

Expanding the toolbox of the biology and electronics mutual conjunction is a primary aim of bioelectronics. The organic electrochemical transistor (OECT) has undeniably become a predominant device for mixed conduction materials, offering impressive transconduction properties alongside a relatively simple device architecture. In this review, we focus on the discussion of recent material developments in the area of mixed conductors for bioelectronic applications by means of thorough structure-property investigation and analysis of current challenges.

Dual emission in purely organic materials for optoelectronic applications.

Purely organic molecules, which emit light by dual emissive (DE) pathways, have received increased attention in the last decade. These materials are now being utilized in practical optoelectronic, sensing and biomedical applications. In order to further extend the application of the DE emitters, it is crucial to gain a fundamental understanding of the links between the molecular structure and the underlying photophysical processes.

Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials.

We investigate a series of D-A molecules consisting of spiro[acridan-9,9'-fluorene] as the donor and 2-phenylenepyrimidine as the acceptor. In two of the materials, a spiro center effectively electronically isolates the D unit from (consequently) optically innocent yet structurally influential adamantyl side groups. In a third material, adamantyl groups attached directly to the acceptor strongly influence the electronic properties.

Delayed Blue Fluorescence via Upper-Triplet State Crossing from C-C Bonded Donor-Acceptor Charge Transfer Molecules with Azatriangulene Cores.

We report the synthesis and structural and photophysical characterization of two series of molecules with functionalized azatriangulene electron donor cores and three pendant electron acceptor units. The presented donor and acceptor units are joined by C-C bonds, instead of the usual C-heteroatom bonds often found in thermally activated delayed fluorescence (TADF) emitters. The effects of the donor-acceptor strength and donor-acceptor dihedral angle on the emission properties are assessed.

Deep-Blue High-Efficiency TTA OLED Using Para- and Meta-Conjugated Cyanotriphenylbenzene and Carbazole Derivatives as Emitter and Host.

Elaboration of the appropriate host materials proved to be not less important for the fabrication of a highly efficient OLED than the design of emitters. In the present work, we show how by simple variation of molecular structure both blue emitters exhibiting delayed fluorescence and ambipolar high triplet energy hosts can be obtained. The compounds with a para-junction revealed higher thermal stability (T up to 480 °C), lower ionization potentials (5.