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Abstract Twisted moiré photonic crystal is an optical analog of twisted graphene or twisted transition metal dichalcogenide bilayers. In this paper, we report the fabrication of twisted moiré photonic crystals and randomized moiré photonic crystals and their use in enhanced extraction of light in light-emitting diodes (LEDs). Fractional diffraction orders from randomized moiré photonic crystals are more uniform than those from moiré photonic crystals. Extraction efficiencies of 76.5%, 77.8% and 79.5% into glass substrate are predicted in simulations of LED patterned with twisted moiré photonic crystals, defect-containing photonic crystals and random moiré photonic crystals, respectively, at 584 nm. Extraction efficiencies of optically pumped LEDs with 2D perovskite (BA)2(MA)n−1PbnI3n+1ofn= 3 and (5-(2′-pyridyl)-tetrazolato)(3-CF3−5-(2′-pyridyl)pyrazolato) platinum(II) (PtD) have been measured.
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Described herein are the synthesis, structure, and photophysics of the iodo-substituted cyclic trinuclear copper( i ) complex, Cu 3 [4-I-3,5-(CF 3 ) 2 Pz] 3 supported by a highly-fluorinated pyrazolate in comparison with its previously reported 4-Br/4-Cl analogues. The crystal structure is stabilised by multiple supramolecular interactions of Cu 3 ⋯I and hydrogen/halogen bonding. The photophysical properties and supramolecular interactions are investigated experimentally/computationally for all three 4-halo complexes vis-à-vis relativistic effects.more » « less
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π-stacking in ground-state dimers/trimers/tetramers ofN-butoxyphenyl(naphthalene)diimide (BNDI) exceeds 50 kcal ⋅ mol−1in strength, drastically surpassing that for the*3[pyrene]2excimer (∼30 kcal ⋅ mol−1; formal bond order = 1) and similar to other weak-to-moderate classical covalent bonds. Cooperative π-stacking in triclinic (BNDI-T) and monoclinic (BNDI-M) polymorphs effects unusually large linear thermal expansion coefficients (αa, αb, αc, β) of (452, −16.8, −154, 273) × 10−6⋅ K−1and (70.1, −44.7, 163, 177) × 10−6⋅ K−1, respectively. BNDI-T exhibits highly reversible thermochromism over a 300-K range, manifest by color changes from orange (ambient temperature) toward red (cryogenic temperatures) or yellow (375 K), with repeated thermal cycling sustained for over at least 2 y.more » « less
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null (Ed.)Described herein is the synthesis and photophysics of two tetranuclear copper complexes, {[3,5-(Pr i ) 2 ,4-(Br)Pz]Cu} 4 and {[3-(CF 3 ),5-(Bu t )Pz]Cu} 4 tailor-designed by manipulating the pyrazolyl ring substituents. Unlike their trinuclear analogues, the luminescence of the tetranuclear species is molecular (not supramolecular) in nature with extremely high solid-state quantum yields of ∼80% at room temperature.more » « less
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A recently synthesized photoluminescent organic acceptor, 5,10-dimethyl-5,10-diaza[5]helicene is shown to react with dicyanoaurate anions to form a 2D network N , N -dimethylaza[5]helicene dicyanoaurate. The structure of the synthesized complex was investigated via X-ray crystallography showing the presence of [Au(CN) 2 ] − dimers and monomers within the helicene framework. Photophysical measurements between 298 K and 10 K indicate quenching of the [Au(CN) 2 ] − anion by 5,10-dimethyl-5,10-diaza[5]helicene via an electron transfer. A Stern–Volmer and Rehm–Weller analysis shows that this is a result of quenching from transfer of an electron from [Au(CN) 2 ] − anions to 5,10-dimethyl-5,10-diaza[5]helicene as opposed to resonance energy transfer. DFT calculations were performed to support the assignment of an electron transfer.more » « less
