Modulation of conductance using light-induced morphological change of a layered π-structure

Photoinduced aggregation-disaggregation behaviour of a tetraphenylethene (TPE)-based molecule has been reversibly achieved upon photoisomerization of a photochromic dihydropyrene (DHP)-conjugated TPE derivative. The DHP-TPE conjugate forms planar stacks because of its aggregation. The highly conjugated pi-system in the DHP form displays a high conductance. The conductance results from pi-conjugation of the stacked aromatic system. Upon photoisomerization, the planar aromatic dihydropyrene (DHP) units convert to non-planar cyclophanediene (CPD) units. This DHP -> CPD photoisomerization results in the disruption of the pi-conjugation as well as the morphology of the well-stacked pi-system. Thus, the conductance of the photoisomerized system in the CPD form drops drastically. Upon exposure to UV light or heating, the photoisomerized sample in the CPD-form reverts to the DHP form. This reversal of the CPD to the DHP re-establishes the aggregation through pi-stacking and the restoration of the high conductance of the sample. This work demonstrates a light-tunable switching of bulk conductance through the aggregation-disaggregation and morphological modulation of an organic system.

Automated summary

Researchers have achieved reversible aggregation-disaggregation behavior of a tetraphenylethene (TPE)-based molecule through photochemical reactions. The change in the molecule's morphology due to the reactions significantly affects its conductance.