arXiv subjects

Anna Popczyk

Publications and source records attributed to Anna Popczyk.

3 recordsLinked to original sources

arXiv2026

Sky-blue Solution-processed TADF and Hyperfluorescent OLEDs via a High-Work-Function PEDOT:PSS:PFI Hole Injection Layer

Solution-processed OLEDs offer a scalable route to large-area devices, but achieving competitive efficiency in multilayer stacks remains a challenge due to difficulties in hole injection as well as solvent orthogonality between layers. A hole injection layer (HIL) based on a blend of PEDOT:PSS and a perfluorinated ionomer (PFI) addresses both challenges simultaneously: surface segregation of PFI during film drying creates a high-work-function interface improving hole injection into high-ionisation potential host materials, while the insolubility of the blend in aromatic solvents prevents intermixing with subsequently deposited layers. Using this HIL with a solution-processed mCPCN:SpiroAC-TRZ emissive layer, sky-blue OLEDs with a peak external quantum efficiency (EQEmax) of 21.7%, an external quantum efficiency (EQE) of 20.2% at 100 cd m-2, a peak luminance of 29,000 cd m-2 and a full width at half maximum (FWHM) emission linewidth of 69 nm are demonstrated. The PFI-based HIL approach is extended to the photochemically stable TADF emitter 5TCzBN (EQEmax 18.4%, FWHM 73 nm) and to sensitized / hyperfluorescent OLEDs incorporating the multi-resonance TADF terminal emitters n-DABNA (EQEmax 22.8%, FWHM 26 nm) and the dendrimer TCzBN-BMes (EQEmax 20.4%, FWHM 29 nm). These results establish the PEDOT:PSS:PFI HIL as a broadly compatible platform for high-performance solution-processed TADF OLEDs.

physics.app-ph↗

arXiv2025

DNA Sensing with Whispering Gallery Mode Microlasers

Nucleic acid sensing is crucial for advancing diagnostics, therapeutic monitoring and molecu-lar biology research, by enabling the precise identification of DNA and RNA interactions. Here, we present an innovative sensing platform based on DNA-functionalized whispering gallery mode (WGM) microlasers. By correlating spectral shifts in laser emission to changes in refractive index, we demonstrate real-time detection of DNA hybridization and structural changes. The addition of gold nanoparticles to the DNA strands significantly enhances sensi-tivity, and labeling exclusively the sensing strand or a hairpin strand eliminates the need for secondary labeling of the target strand. We further show that ionic strength influences DNA compactness, and we introduce a hairpin-based system as a dual-purpose sensor and con-trolled release mechanism for potential drug delivery. This versatile WGM-based platform of-fers promise for sequence-specific nucleic acid sensing, multiplexed detection, and in vivo ap-plications in diagnostics and cellular research.

physics.optics↗

arXiv2025

Electrochemically induced hyperfluorescence based on the formation of charge-transfer excimers

Used extensively in sensing applications, the application of solution-state electrochemiluminescent devices (ECLDs) in lighting and displays has been constrained by their low luminance and short operational lifetime. Here, we report a record improvement in the luminance, efficiency, and operational longevity of ECLDs by introducing electrochemically induced hyperfluorescence (ECiHF) and demonstrate its use in a calligraphic display. We use the double-decker arrangement assumed by the electron donor and acceptor segments of the molecule TpAT-tFFO to realize thermally activated delayed fluorescence from an electrogenerated charge-transfer (CT) excimer state and a subsequent energy transfer to the rubrene emitter TBRb. ECLDs based on this strategy achieve an unprecedented luminance of >6,200 cd/m2 and their operational lifetime is more than 10-fold longer than all previous ECLDs with meaningful efficiency or brightness. We identify energy level alignment between excimer and emitter as a crucial factor for efficient ECiHF; spectroelectrochemical analysis reveals that devices with energy gaps < 0.4 eV operate on a pure excimer mechanism across a wide range of frequencies. Our findings highlight the potential of ECiHF for improving ECLDs and pave the way to commercial applications of this form of fluid light.

physics.optics↗