Odd-Even Effect in Charge Transfer Complexes through the Regulation of the Alkyl Chain

Charge transfer (CT) complexes formed by donor-acceptor (D-A) pairs play a critical role in organic optoelectronic devices, where the CT effect is highly correlated with molecular packing and intermolecular interaction. There are still challenges in exploring the mechanisms of charge transfer in the noncrystal state. Most studies regulated intermolecular charge transfer by altering the pi-conjugated backbone and substituents, which would lead to some uncertainties in the packing-property relationship. Herein, we utilized triazatruxene (TAT) with different alkyls as donors and 1,3,5-benzenetricarbonitrile (TCNPh) derivatives as acceptors. The systems of the CT complex were constructed by simply grinding the donor-acceptor mixture to study the role of molecular arrangement in charge transfer, in which an obvious odd-even effect could be observed. Thus, our study further enriched the odd-even effect of alkyl chain regulation, allowing for a more profound understanding of the relationship among aggregation structures, CT interactions, and optoelectronic characteristics of the CT complex.