Lattice-guided assembly of optoelectronically-active π-conjugated peptides on 1D van der Waals single crystals

The utility of organic functional units for high-performance materials and devices is highly dependent on the formation of ordered domains across extended regimes. As such, the development of synthetic approaches to achieve precisely ordered material building blocks, a process often complicated by the dynamic and sensitive nature of supramolecular interactions in many organic molecules, is critical in realizing efficient functional devices and emergent physical properties. To this end, we leveraged the long-range anisotropic ordering intrinsic to a class of 1D van der Waals (vdW) crystals comprised of sub-nanometer-thick transition metal trichalcogenide (MCh3; M = Ti, Zr, Hf, Nb, Ta; Ch = S, Se) chain subunits to guide the assembly of supramolecular π-conjugated peptide building blocks. Through this synthetic strategy, we realized morphologically well-defined organic-inorganic heterointerfaces that display drastically altered photophysical properties and are capable of photocurrent generation. Owing to the structural correspondence between the π-π interactions of the organic quaterthiophene (4T)-based π-conjugated peptides (DDD-4T) and the periodic sulfur ordering along the (100) planes of inorganic niobium sulfide (NbS3) 1D vdW crystals, we found that organic π-conjugated peptide monomers can readily form 1D supramolecular assemblies on the surface of the underlying inorganic crystal. Optimal assembly conditions allowed for the controlled deposition and growth of the peptide assemblies on the crystal surfaces as validated by a combination of fluorescence microscopy, photoluminescence map-ping, Raman spectroscopy, atomic force microscopy, and computational molecular dynamics simula-tions. The resulting DDD-4T/NbS3 heterointerfaced assemblies exhibit a significantly improved visi-ble-range photocurrent generation compared to the freestanding π-conjugated peptide films assembled from solution. Altogether, our study demonstrates the important role of lattice matching in the for-mation of ordered low-dimensional organic-inorganic heterointerfaces, offering a new approach to-wards directing the assembly of supramolecular organic building blocks endowed with improved opti-cal and optoelectronic properties.