We herein report a new highly efficient green emissive hot-exciton molecule, 1,4-bis((4′-diphenylamino-3-cyano-[1,1′-biphenyl]-4-yl)ethynyl)-2,5-bis(2-ethylhexyloxy)benzene (2EHO-TPA-CNPE) that consists of an extended D′–π′–A–π–D–π–A–π′–D′ molecular π-system with diphenylamino end units (D′) and ethynylene/phenylene spacers (π/π′). The new molecule exhibits high photoluminescence (PL) quantum efficiencies (Φ_PL = 0.95 (solution) and 0.45 (spin-coated neat thin-film)), and a strong PL solvatochromic behavior revealing significant changes in excited state energies/characteristics (locally excited (LE) → hybridized local and charge transfer (HLCT) → charge-transfer (CT)) depending on solvent polarity. Highly efficient (radiative exciton yield (η_r) = 50–59% ≫ 25%) green-emitting OLEDs were fabricated in a conventional device architecture by employing (non-)doped thin-films reaching a maximum current efficiency (CE_max) of 12.0 cd A⁻¹ and a maximum external quantum efficiency (EQE_max) of 5.5%. The emission profile of the non-doped OLED has CIE 1976 (u′, v′) chromaticity coordinates of (0.10, 0.55) corresponding to a night vision imaging system (NVIS) compatible Green A region. 2EHO-TPA-CNPE-based OLED devices of industrial relevance were also fabricated by ink-jet printing the emissive layer and by fabricating an inverted architecture, which possessed respectable device performances of 2.4–6.1 cd A⁻¹. The solid-state solvation effect in OLED devices yields HLCT electronic behavior resulting in high η_r's, which is confirmed by TDDFT to originate from energetically/spatially favorable reverse intersystem crossings (RISCs) (T_2/3 → S₁). As a unique observation, delayed fluorescence due to this RISC was evident in the PL decay lifetime measurement with a ns-scale lifetime of ∼10 ns. These results clearly allow a better understanding of the structure–photophysical property–electroluminescence relationships in this new class of oligo(p-phenyleneethynylene)-based hot-exciton molecules, and it could open up new opportunities for high-performance solution-processed optoelectronic/sensing applications.

Advanced anti‐counterfeiting and authentication approaches are in urgent need of the rapidly digitizing society. Physically unclonable functions (PUFs) attract significant attention as a new‐generation security primitive. The challenge is design and generation of multi‐color PUFs that can be universally applicable to objects of varied composition, geometry, and rigidity. Herein, tattoo‐like multi‐color fluorescent PUFs are proposed and demonstrated. Multi‐channel optical responses are created by electrospraying of polymers that contain semiconductor nanocrystals with precisely defined photoluminescence. The universality of this approach enables the use of dot and dot‐in‐rod geometries with unique optical characteristics. The fabricated multi‐color PUFs are then transferred to a target object by using a temporary tattoo approach. Digitized keys generated from the red, green and blue fluorescence channels facilitate large encoding capacity and rapid authentication. Feature matching algorithms complement the authentication by direct image comparison, effectively alleviating constraints associated with imaging conditions. The strategy that paves the way for the development of practical, cost‐effective, and secure anticounterfeiting systems is presented.