Tuning Photophysical Properties of Acceptor-Donor-Acceptor Di-2-(2-oxindolin-3-ylidene) Malononitrile Materials via Extended π-Conjugation: A Joint Experimental and Theoretical Study - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Materials Année : 2023

Tuning Photophysical Properties of Acceptor-Donor-Acceptor Di-2-(2-oxindolin-3-ylidene) Malononitrile Materials via Extended π-Conjugation: A Joint Experimental and Theoretical Study

Résumé

Organic semiconductor (OSC) materials with a high electron affinity are required for many optoelectronic applications. In this work a series of twelve novel acceptor-donor-acceptor (A-D-A) materials with low-lying LUMO energy levels are designed, synthesized, and characterized. In this strategy, two acceptor dyes, isatin and its dicyanovinyl derivatives are connected by various π-bridges. We have varied the π-conjugation length of the central core and altered the linkage position of the acceptor core (4-position vs. 6-position of the phenyl ring of the isatin moiety) to study the effect of extended π-conjugation and point of linkage of the acceptor on optical and electrochemical properties of the new dyes. Density functional theory (DFT) and time-dependent DFT (TD-DFT) studies have been performed to gain an insight into their electronic properties by determining the energy levels and maps of the HOMO, LUMO as well as HOMO-LUMO gap (energy differences between the highest occupied and lowest unoccupied molecular orbitals). Our findings demonstrate that with increasing the acceptor strength and π-conjugation length of the 2 core, the wavelength of the longest absorption maximum as well as their respective extinction coefficients are enhanced, which resulted in band-gap reduction either by lowering the LUMO and or raising the HOMO energy level of the molecules. Space-charge-limited current measurements (SCLC) were investigated to probe the electron mobility of these molecules. Electron only devices were fabricated by the spin-coating and the trap-limited electron mobility was calculated using Mott-Gurney law. 10a exhibited an intrinsic moderate electron mobility of 8.94×10-4 cm 2 V-1 s-1. The potential practical utility of these materials as an electron-transport material for perovskite solar cells (PSCs) has been demonstrated.
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hal-04471733 , version 1 (21-02-2024)

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Shiwei Ren, Amirhossein Habibi, Pingping Ni, Yuexing Zhang, Abderrahim Yassar. Tuning Photophysical Properties of Acceptor-Donor-Acceptor Di-2-(2-oxindolin-3-ylidene) Malononitrile Materials via Extended π-Conjugation: A Joint Experimental and Theoretical Study. Materials, 2023, 16 (19), pp.6410. ⟨10.3390/ma16196410⟩. ⟨hal-04471733⟩

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