Liquid Metal-Enabled Galvanic Electrocrystallization\nof Charge-Transfer Complexes

Charge-transfer complexes\n(CTCs), which comprise ordered assemblies\nof electron acceptor and donor units, represent a mature group of\nadvanced materials. These structures offer unique features, such as\nintrinsic conductivity, one-dimensional morphology, and tailorable\nchemistry. To enable the exploitation of CTCs for real-world applications,\nwe investigate CTC nucleation and growth and develop scalable manufacturing\nmethods for their incorporation into electronic systems. In the present\nwork, we combine the unique features of CTCs and liquid metals (LMs)\nto investigate the galvanic electrocrystallization of tetracyanoquinodimethane\ncomplexes with silver (AgTCNQ) and copper (CuTCNQ). The eutectic alloy\nof gallium and indium (EGaIn) has been shown to be effective in nucleating\nCTC crystals. EGaIn reduces TCNQ and accumulates metallic precursors\nat the LM/solution interface via galvanic reduction and stabilization\nof the metal oxide nanoparticles. This enables the efficient formation\nand growth of conductive CTC crystals on patterned electronics without\nthe need for an external input. The AgTCNQ wirelike crystals could\ntransfer the autogenous potential of EGaIn, leading to their decoration\nwith Ag nanoparticles. The AgTCNQ crystals grow longer than the CuTCNQ\ncrystals, enabling the interconnection of electronic tracks. This\nknowledge opens new pathways for scalable CTC crystallization and\ndirect incorporation into electronic systems.