Browsing by Author "Dunietz, Barry D."

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    Enhancing charge mobilities in organic semiconductors by selective fluorination: A design approach based on a quantum mechanical perspective
    (Royal Society of Chemistry, 2017-08-14) Maiti, Buddhadev; Schubert, Alexander; Sarkar, Sunandan; Wang, Kunlun; Li, Zhe; Geva, Eitan; Twieg, Robert J.; Dunietz, Barry D.
    Selective fluorination of organic semiconducting molecules is proposed as a means to achieving enhanced hole mobility. Naphthalene is examined here as a root molecular system with fluorination performed at various sites. Our quantum chemical calculations show that selective fluorination can enhance attractive intermolecular interactions while reducing charge trapping. Those observations suggest a design principle whereby fluorination is utilized for achieving high charge mobilities in the crystalline form. The utility of this design principle is demonstrated through an application to perylene, which is an important building block of organic semiconducting materials. We also show that a quantum mechanical perspective of nuclear degrees of freedom is crucial for a reliable description of charge transport. © 2017 The Royal Society of Chemistry.
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    Enhancing fluorescence and lowering the optical gap through C[dbnd]P doping of a π-conjugated molecular backbone: A computational-based design approach
    (Elsevier B.V., 2021-11-20) Sarkar, Sunandan; Durairaj, Pandiselvi; Protasiewicz, John D.; Dunietz, Barry D.
    Design principles of organic fluorescent materials are investigated at the molecular level using a first-principles-based computational approach. The design approach incorporates hetero atoms into a conjugated cyclic skeleton by introducing C[dbnd]P bonds. In particular we report the design of a molecular system of an extended conjugation system that maintains its planarity across the full system, achieving low lying electronic excited states of large oscillator strengths. We also present calculations that confirm the competing process of internal system crossing to be too slow for affecting the actual relaxation following photexcitation. © 2021 The Author(s)
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    Luminescent 1H-1,3-benzazaphospholes
    (Royal Society of Chemistry, 2022-12-22) Evariste, Sloane; Harrison, Alexandra M.; Sarkar, Sunandan; Rheingold, Arnold L.; Dunietz, Barry D.; Heinicke, Joachim W.; Delgado Rosario, Emalyn; Yoon, Sungwoon; Teets, Thomas S.; Protasiewicz, John D.
    2-R-1H-1,3-Benzazaphospholes (R-BAPs) are an interesting class of σ2P heterocycles containing P = C bonds. While closely related 2-R-1,3-benzoxaphospholes (R-BOPs) have been shown to be highly photoluminescent materials depending on specific R substituents, photoluminescence of R-BAPs has been previously limited to an example having a fused carbazole ring system. Here we detail the synthesis and structural characterization of a new R-BAP (3c, R = 2,2′-dithiophene), and compare its photoluminescence against two previously reported R-BAPs (3a, R, R′ = Me and 3b, R = 2-thiophene). The significant fluorescence displayed by the thiophene derivatives 3b (φ = 0.53) and 3c (φ = 0.12) stands in contrast to the weakly emissive methyl substituted analogue 3a (φ = 0.08). Comparative computational investigations of 3a-c offer insights into the interplay between structure-function relationships affecting excited state relaxation processes. © 2023 The Royal Society of Chemistry.