5 results found
Chen H-Y, Schweicher G, Planells M, et al., 2018, Crystal Engineering of Dibenzothiophenothieno[3,2-b]thiophene (DBTTT) Isomers for Organic Field-Effect Transistors, CHEMISTRY OF MATERIALS, Vol: 30, Pages: 7587-7592, ISSN: 0897-4756
Chen H, Hurhangee M, Nikolka M, et al., 2017, Dithiopheneindenofluorene (<bold>TIF</bold>) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors, ADVANCED MATERIALS, Vol: 29, ISSN: 0935-9648
Green JP, Cryer SJ, Marafie J, et al., 2017, Synthesis of a Luminescent Arsolo[2,3-d:5,4-d']bis(thiazole) Building Block and Comparison to Its Phosphole Analogue, Organometallics, Vol: 36, Pages: 2632-2636, ISSN: 0276-7333
The synthesis of 4-phenyl-4H-arsolo[2,3-d:5,4-d′]bis(thiazole) is reported, and its properties are compared to those of the previously prepared phosphole analogue. By comparison of their single-crystal structures, the harmonic oscillator model of heterocyclic electron delocalization (HOMHED) was used to directly compare the aromatic character of the two systems. The findings demonstrate that, although both compounds can be considered aromatic, the phosphole-containing compound had a greater degree of aromatic character than its arsole analogue. The arsole derivative exhibited excellent stability in ambient air with no formation of the arsole oxide observed upon storage. The absorption and photoluminescence spectra of the arsole derivate were subtly altered in comparison to the phosphole derivative, suggesting that changing pnictogenic atoms in such fused-ring systems to heavier analogues could be a viable way of tuning both the ambient stability and optoelectronic properties of such materials.
Nielsen CB, Holliday S, Chen H, et al., 2015, Non-fullerene electron acceptors for use in organic solar cells, Accounts of Chemical Research, Vol: 48, Pages: 2803-2812, ISSN: 1520-4898
The active layer in a solution processed organic photovoltaic device comprises a light absorbing electron donor semiconductor, typically a polymer, and an electron accepting fullerene acceptor. Although there has been huge effort targeted to optimize the absorbing, energetic, and transport properties of the donor material, fullerenes remain as the exclusive electron acceptor in all high performance devices. Very recently, some new non-fullerene acceptors have been demonstrated to outperform fullerenes in comparative devices. This Account describes this progress, discussing molecular design considerations and the structure–property relationships that are emerging.The motivation to replace fullerene acceptors stems from their synthetic inflexibility, leading to constraints in manipulating frontier energy levels, as well as poor absorption in the solar spectrum range, and an inherent tendency to undergo postfabrication crystallization, resulting in device instability. New acceptors have to address these limitations, providing tunable absorption with high extinction coefficients, thus contributing to device photocurrent. The ability to vary and optimize the lowest unoccupied molecular orbital (LUMO) energy level for a specific donor polymer is also an important requirement, ensuring minimal energy loss on electron transfer and as high an internal voltage as possible. Initially perylene diimide acceptors were evaluated as promising acceptor materials. These electron deficient aromatic molecules can exhibit good electron transport, facilitated by close packed herringbone crystal motifs, and their energy levels can be synthetically tuned. The principal drawback of this class of materials, their tendency to crystallize on too large a length scale for an optimal heterojunction nanostructure, has been shown to be overcome through introduction of conformation twisting through steric effects. This has been primarily achieved by coupling two units together, forming dimers
Rumer JW, Schroeder BC, Nielsen CB, et al., 2014, Bis-lactam-based donor polymers for organic solar cells: Evolution by design, Thin Solid Films, Vol: 560, Pages: 82-85, ISSN: 0040-6090
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