Self-Assembled 3,4,9,10-Perylenetetracarboxylic Acid Dianhydride is a Molecular Graphite

Viable organic charge storage materials must display rapid cation insertion. Typically, these materials are composed of monomers that undergo slow outer-sphere electron transfer coupled to significant bond rearrangement. Here we show that 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) self assembles into an organic material that undergoes graphite-like cation insertion-coupled electron transfer rather than forming a radical anion or an enolate, as previously thought. This charge storage pathway is enabled by a delocalized band structure across the material and minimal bond rearrangement in individual PTCDA molecules upon reduction. Based on these results, we propose that self-assembled PTCDA is best thought of as a synthetically tunable “molecular graphite.” This finding points towards a new bottom-up design strategy for self-assembled organic materials with efficient charge storage pathways.