Highly Efficient Indoor Perovskite Solar Cells with 40% Efficiency Using Perylene Diimide-Based Zwitterionic Cathode Interlayers.

Metal halide perovskites are ideal candidates for indoor photovoltaics (IPVs) due to their tunable bandgaps, which allow the active layers to be optimized for artificial light sources. However, significant non-radiative carrier recombination under low-light conditions has limited the full potential of perovskite-based IPVs. To address this challenge, an integration of perylene diimide (PDI)-based sulfobetaines as cathode interlayers (CILs) is proposed and the impact of varying alkyl chain length (from 1,2-ethylene to 1,5-pentylene) between the cationic and the anionic moieties is examined.

1,4-Dihydropyrrolo[3,2-]pyrrole modified with dibenzoxazepine: a highly efficient core for charge-transfer-based OLED emitters.

The present work is focused on designing novel heteroaromatic systems, formally a hybrid of dibenzo[,]oxazepines and 1,4-dihydropyrrolo[3,2-]pyrroles (DHPPs). Straightforward synthesis affords a family of rigid, centrosymmetric, π-expanded aromatic heterocycles amenable to facile post-functionalization. The rigidified molecular architecture is responsible for several key photophysical features including (1) the excellent blue colour purity (full width at half maximum parameter = 0.

Host-Matrix Interactions and Molecular Functionalization: Shaping the Delayed Emission Properties of Indenophenanthridine Derivatives.

The advancement of organic room temperature phosphorescence (RTP) materials has attracted considerable interest owing to their extensive applications. Their distinct advantages, including a metal-free composition, low toxicity, and facile synthesis under ambient conditions, make them highly desirable. This study examines the delayed fluorescence (DF) and RTP of metal-free, amorphous indenophenanthridine (IND)-based derivatives (1-10) and provides insights into molecular functionalisation and host matrix effects on delayed emission (RTP and DF).

An unprecedented roll-off ratio in high-performing red TADF OLED emitters featuring 2,3-indole-annulated naphthalene imide and auxiliary donors.

The capability of organic emitters to harvest triplet excitons a thermally activated delayed fluorescence (TADF) process has opened a new era in organic optoelectronics. Nevertheless, low brightness, and consequently an insufficient roll-off ratio, constitutes a bottleneck for their practical applications in the domain of organic light-emitting diodes (OLEDs). To address this formidable challenge, we developed a new design of desymmetrized naphthalimide (NMI) featuring an annulated indole with a set of auxiliary donors on its periphery.

Regioisomerism vs Conformation: Impact of Molecular Design on the Emission Pathway in Organic Light-Emitting Device Emitters.

Despite the design and proposal of several new structural motifs as thermally activated delayed fluorescent (TADF) emitters for organic light-emitting device (OLED) applications, the nature of their interaction with the host matrix in the emissive layer of the device and their influence on observed photophysical outputs remain unclear. To address this issue, we present, for the first time, the use of up to four regioisomers bearing a donor-acceptor-donor electronic structure based on the desymmetrized naphthalene benzimidazole scaffold, equipped with various electron-donating units and possessing distinguished conformational lability. Quantum chemical calculations allow us to identify the most favorable conformations adopted by the electron-rich groups across the entire pool of regioisomers.

Application of the Heavy-Atom Effect for (Sub)microsecond Thermally Activated Delayed Fluorescence and an All-Organic Light-Emitting Device with Low-Efficiency Roll-off.

The feature of abundant and environmentally friendly heavy atoms (HAs) like bromine to accelerate spin-forbidden transitions in organic molecules has been known for years. In combination with the easiness of incorporation, bromine derivatives of organic emitters showing thermally activated delayed fluorescence (TADF) emerge as a cheap and efficient solution for the slow reverse intersystem crossing (rISC) problem in such emitters and strong efficiency roll-off of all-organic light-emitting diodes (OLEDs). Here, we present a comprehensive photophysical study of a emitter reported previously and its hexabromo derivative showing a remarkable enhancement of rISC of up to 9 times and a short lifetime of delayed fluorescence of 2 μs.

Shedding Light on Highly Emissive 1,4-Dihydropyrrolo[3,2-b]pyrrole Derivatives: Synthesis and Aggregate-Dependent Emission.

Three tetraaryl-1,4-dihydropyrrolo[3,2-b]pyrrole derivatives containing different number of long alkoxy chains (2, 4 and 6) were synthesized, characterized and applied in Organic Light Emitting Diodes (OLEDs). The compounds showed good emission properties with Photoluminescence Quantum Yields (PLQYs) higher than 80 % in solution and 50 % in solid state (thin film). The solvatochromism results revealed a pronounced vibronic emission in methylcyclohexane and toluene, characterized by two distinct sharp emission peaks and a small redshift in the following order: methylcyclohexane>toluene>dichloromethane>tetrahydrofuran>acetonitrile.

Electroactive Dyes Based on 1,8-Naphthalimide with Acetylene Linkers as Promising OLED Materials - the Relationship Between Structure and Photophysical Properties.

Four A-π-D-π-A type small organic molecules with 1,8-naphthalimide motifs were successfully synthesised. The designed compounds are built of two 1,8-naphthalimide units linked via ethynyl π-linkages with selected functionalised donor motifs i. e.

Facile Functionalization of Ambipolar, Nitrogen-Doped PAHs toward Highly Efficient TADF OLED Emitters.

Despite promising optoelectronic features of N-doped polycyclic aromatic hydrocarbons (PAHs), their use as functional materials remains underdeveloped due to their limited post-functionalization. Facing this challenge, a novel design of N-doped PAHs with D-A-D electronic structure for thermally activated delayed fluorescence (TADF) emitters was performed. Implementing a set of auxiliary donors at the meta position of the protruding phenyl ring of quinoxaline triggers an increase in the charge-transfer property simultaneously decreasing the delayed fluorescence lifetime.

V-shaped donor-acceptor organic emitters. A new approach towards efficient TADF OLED devices.

We report the synthesis and characterization of a series of donor-acceptor TADF emitters with a new architecture, where the donor moiety and the dibenzazepine-based acceptor moiety are separated by a phenylene linker in a V-shaped spatial arrangement. Such spatial separation and electronic decoupling between the donor and the acceptor moieties leads to low singlet-triplet energy gaps and favors efficient exciton up-conversion.

Tandem rigidification and π-extension as a key tool for the development of a narrow linewidth yellow hyperfluorescent OLED system.

Hyperfluorescence (HF), a relatively new phenomenon utilizing the transfer of excitons between two luminophores, requires careful pairwise tuning of molecular energy levels and is proposed to be the crucial step towards the development of new, highly effective OLED systems. To date, barely few HF yellow emitters with desired narrowband emission but moderate external quantum efficiency (EQE < 20%) have been reported. This is because a systematic strategy embracing both Förster resonance energy transfer (FRET) and triplet to singlet (TTS) transition as complementary mechanisms for effective exciton transfer has not yet been proposed.

Dibenzophenazine-Based TADF Emitters as Dual Electrochromic and Electroluminescence Materials.

Previous work has reported the synthesis of donor-acceptor-donor molecules based on dibenzophenazine acceptor group, presenting thermally activated delayed fluorescent (TADF) properties and their application in the assembly of highly efficient electroluminescent devices. Herein, we focus on the characterisation of charge carrier species through UV-Vis-NIR spectroelectrochemical and potentiostatic EPR techniques, in addition to the investigation of electropolymerisation properties of some compounds depicted in this study. The promising electrochromic features of both small molecules and conjugated polymers led to the assembly and investigation of electrochromic devices, evidencing the materials' versatility, applied in such different approaches as electrochromic windows and electroluminescent devices.

Comparative study of thermally activated delayed fluorescent properties of donor-acceptor and donor-acceptor-donor architectures based on phenoxazine and dibenzo[]phenazine.

A new thermally activated delayed fluorescence (TADF) compound based on a donor-acceptor (D-A) architecture (D = phenoxazine; A = dibenzo[]phenazine) has been developed, and its photophysical properties were characterized. The D-A compound is applicable as an emitting material for efficient organic light-emitting diodes (OLEDs), and its external quantum efficiency (EQE) exceeds the theoretical maximum of those with prompt fluorescent emitters. Most importantly, comparative study of the D-A molecule and its D-A-D counterpart from the viewpoints of the experiments and theoretical calculations revealed the effect of the number of the electron donor on the thermally activated delayed fluorescent behavior.

Dual-photofunctional organogermanium compound based on donor-acceptor-donor architecture.

A dual-photofunctional organogermanium compound based on a donor-acceptor-donor architecture that exhibits thermally activated delayed fluorescence and mechano-responsive luminochromism has been developed. The developed compound was successfully applied as an emitter for efficient organic light-emitting diodes.

Novel Easy to Synthesize Benzonitrile Compounds with Mixed Carbazole and Phenoxazine Substituents Exhibiting Dual Emission and TADF Properties.

The photophysical and electrochemical properties of a new class of fluorinated benzonitrile compounds substituted with mixed phenoxazine and carbazole units have been investigated. When absorbing in a large range of the UV-vis spectrum due to both localized and charge-transfer absorptions, these compounds show dual broad emission in solution and intense emission in PMMA films, with photoluminescence quantum yields changing from a few percent in solution to 18% in a more rigid environment. The compounds also exhibit thermally activated delayed fluorescence demonstrated by the role of oxygen in the quenching of delayed fluorescence and by time-resolved luminescence studies, with an efficiency directly related to the number of phenoxazine substituents.

Modular Nitrogen-Doped Concave Polycyclic Aromatic Hydrocarbons for High-Performance Organic Light-Emitting Diodes with Tunable Emission Mechanisms.

Although bowl-shaped N-pyrrolic polycyclic aromatic hydrocarbons (PAHs) can achieve excellent electron-donating ability, their application for optoelectronics is hampered by typically low photoluminescence quantum yields (PLQYs). To address this issue, we report the synthesis and characterization of a series of curved and fully conjugated nitrogen-doped PAHs. Through structural modifications to the electron-accepting moiety, we are able to switch the mechanism of luminescence between thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), and to tune the overall PLQY in the range from 9 % to 86 %.

Organic Thermoelectric Materials as the Waste Heat Remedy.

The primary reason behind the search for novel organic materials for application in thermoelectric devices is the toxicity of inorganic substances and the difficulties associated with their processing for the production of thin, flexible layers. When Thomas Seebeck described a new phenomenon in Berlin in 1820, nobody could have predicted the future applications of the thermoelectric effect. Now, thermoelectric generators (TEGs) are used in watches, and thermoelectric coolers (TECs) are applied in cars, computers, and various laboratory equipment.

Electrochemically Deposited Zinc (Tetraamino)phthalocyanine as a Light-activated Antimicrobial Coating Effective against .

Light-activated antimicrobial coatings are currently considered to be a promising approach for the prevention of nosocomial infections. In this work, we present a straightforward strategy for the deposition of a photoactive biocidal organic layer of zinc (tetraamino)phthalocyanine (ZnPcNH) in an electrochemical oxidative process. The chemical structure and morphology of the resulting layer are widely characterized by microscopic and spectroscopic techniques, while its ability to photogenerate reactive oxygen species (ROS) is investigated in situ by UV-Vis spectroscopy with α-terpinene or 1,3-diphenylisobenzofuran as a chemical trap.

The Impact of C Insertion into a Carbazole Donor on the Physicochemical Properties of Dibenzo[a,j]phenazine-Cored Donor-Acceptor-Donor Triads.

Novel electron donor-acceptor-donor (D-A-D) compounds comprising dibenzo[a,j]phenazine as the central acceptor core and two 7-membered diarylamines (iminodibenzyl and iminostilbene) as the donors have been designed and synthesized. Investigation of their physicochemical properties revealed the impact of C insertion into well-known carbazole electron donors on the properties of previously reported twisted dibenzo[a,j]phenazine-core D-A-D triads. Slight structural modification caused a drastic change in conformational preference, allowing unique photophysical behavior of dual emission derived from room-temperature phosphorescence and triplet-triplet annihilation.

Covalent Immobilization of Organic Photosensitizers on the Glass Surface: Toward the Formation of the Light-Activated Antimicrobial Nanocoating.

Two highly efficient commercial organic photosensitizers-azure A (AA) and 5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin (APTPP)-were covalently attached to the glass surface to form a photoactive monolayer. The proposed straightforward strategy consists of three steps, i.e.