(34g) Helical Perylene Diimide Ribbons for Molecular Electronics

In this presentation, I introduce a series of helical perylene diimide (PDI) ribbons as efficient electron acceptors. The ribbons are constructed by fusing perylene diimide units together with a two-carbon bridge. In the first part, we show that these helical ribbons are highly efficient non-fullerene acceptors for organic solar cells. By varying lengths of the ribbons and controlling film morphology in bulkjunction solar cells, we achieved a record power conversion efficiency of ~8.5 %. Femtosecond transient absorption spectroscopy reveals both electron and hole transfer processes at the donor acceptor interfaces. Atomic force microscopy reveals a mesh-like network of acceptors with pores that are tens of nanometers in diameter for efficient exciton separation and charge transport. 

In the second part, we demenstrate that these ribbons represent a new molecular design that yields ultra-narrowband organic photodetectors. We fabricate charge collection narrowing photodetectors based on four helical ribbons that differ in the wavelength of their response. The photodetectors made from these materials have narrow spectral response with full-width at half maxima of < 20 nm. The devices shown here are superior by approximately a factor of 5 to those from traditional organic materials due to the narrowness of their response. Moreover, the active layers for the helical ribbon-based photodetectors are solution cast but have performance that is comparable to the state-of-the-art narrowband photodetectors made from methylammonium lead trihalide perovskite single crystals.

References:

[1]J. Am. Chem. Soc. 2014, 136 (22), 8122-8130.

[2]J. Am. Chem. Soc. 2014, 136 (43), 15215-21.

[3]Nat. Commun. 2015, 6, 8242.

[4]J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.6b13093.

[5]J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.6b13089.