Fullerene derivatives are the most common acceptor materials in organic photovoltaics (OPVs) even with their drawbacks, i.e. poor light absorption, limited chemical and energetic tunability, high cost, and morphological instability in devices. Non-fullerene acceptors have been recently reported to give higher OPV performance than fullerenes, eliminating many of their drawbacks; however, these non-fullerene acceptors have complicated structures. We sought to develop new, simpler n-type small molecules by incorporating electron-withdrawing atoms, here nitrogen, into a pentacene core. The goal is to maintain the desirable properties of pentacene, such as high charge carrier mobilities (&gt;1 cm2.V-1.s-1), 2D π-stacking, and good light absorption in the visible spectrum, and use the N-substitution of the pentacene core to lower the LUMO energy close to that of C60. Here, we disclose a base-catalyzed one-pot Friedländer synthesis of tetra-aza-pentancenes (TAPs). Contrary to previous reports, our syntheses do not only yield the non-linear Friedländer products, but also the linear products that are fully aromatized in-situ without an exogenous oxidizing agent. From pre-synthetically engineered starting materials, soluble and stable TAPs can be synthesized. This is an inexpensive, straightforward and easily scalable route to make novel tetra-aza-substituted pentacenes that are promising small molecule acceptors for OPVs.

One-pot Friedländer synthesis of tetra-aza-pentacenes: N-type small molecules for OPV applications

256th National Meeting (2018)

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