A comprehensive analysis of charge transfer effects on donor‐pyrene (bridge)‐acceptor systems using different substituents

Abstract

The alternant polycyclic aromatic hydrocarbon pyrene has photophysical properties that can be tuned with different donor and acceptor substituents. Recently, a D (donor)‐Pyrene (bridge)‐A (acceptor) system, DPA, with the electron donor N,N‐dimethylaniline (DMA), and the electron acceptor trifluoromethylphenyl (TFM), was investigated by means of time‐resolved spectroscopic measurements (J. Phys. Chem. Lett. 2021, 12, 2226–2231). DPA shows great promise for potential applications in organic electronic devices. In this work, we used the ab initio second‐order algebraic diagrammatic construction method ADC(2) to investigate the excited‐state properties of a series of analogous DPA systems, including the originally synthesized DPAs. The additionally investigated substituents were amino, fluorine, and methoxy as donors and nitrile and nitro groups as acceptors. The focus of this work was on characterizing the lowest excited singlet states regarding charge transfer (CT) and local excitation (LE) characters. For the DMA‐pyrene‐TFM system, the ADC(2) calculations show two initial electronic states relevant for interpreting the photodynamics. The bright S1 state is locally excited within the pyrene moiety, and an S2 state is localized ~0.5 eV above S1 and characterized as a donor to pyrene CT state. HOMO and LUMO energies were employed to assess the efficiency of the DPA compounds for organic photovoltaics (OPVs). HOMO‐LUMO and optical gaps were used to estimate power conversion and light‐harvesting efficiencies for practical applications in organic solar cells. Considering the systems using smaller D/A substituents, compounds with the strong acceptor NO2 substituent group show enhanced CT and promising properties for use in OPVs. Some of the other compounds with small substituents are also found to be competitive in this regard.

Influence of Steric Effects on the Emission Behavior of Pyrene-Based Blue Luminogens

“…Polycyclic aromatic hydrocarbons (PAHs) featuring large π-conjugated architectures are a significant category of functional materials by virtue of their remarkable photophysical, electrical, and mechanical performances − and have been successfully applied in diverse fields, ranging from organic field-effect transistors, , organic photovoltaic cells, − and organic/quantum dot light-emitting diodes − to fluorescence sensors. − As one of the extensively used and representative families of PAHs, pyrenes are chemically stable and contain four integrated benzene rings with extended π-electron delocalization . The unique flat aromatic scaffold endows pyrenes with salient properties, such as deep blue fluorescence, high charge carrier mobility, and prominent hole injection capacity, making them excellent candidates for organic optoelectronic materials, chemosensors, and bioimaging applications. − However, the fluorescence output of pyrene aggregates is usually inferior to what can be achieved in their respective solutions, and this hampers their potential high-technological application in fluorescence-relevant areas. , The weakened emission in the aggregated state may be attributed to the facile generation of detrimental substances such as excimers, given that the planar structure of pyrene tends to undergo intense intermolecular π–π stacking interactions once aggregated. Therefore, exploring feasible approaches to promote the aggregate-state fluorescence of pyrenes is of great interest when trying to facilitate their latent applications in organic optoelectronics and other extensive scenarios.…”

Nonadiabatic molecular dynamics with subsystem density functional theory: application to crystalline pentacene

“…To date, multiple NA-MD methods have been developed, ranging from the mixed quantum-classical (MQC) methods such as Ehrenfest [63,64] and trajectory surface hopping (TSH) [65][66][67][68] techniques to semiclassical wave packet propagation and fully quantal [69] methods. Due to their simplicity, low computational cost, and reasonable accuracy, the approximate MQC techniques have found their wide use in modeling NA dynamics in many condensed-matter [70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85] and molecular systems [86][87][88][89]. However, such modeling in extended systems is often hindered by two factors: the intrinsic complexity of quantum dynamics itself and the steeply scaling costs of reliable electronic structure calculations.…”