Single-crystalline Cu₄Bi₄S₉ nanoribbons: Facile synthesis, growth mechanism, and surface photovoltaic properties

Cu-based ternary chalcogenides have received great interest as low-cost alternatives to conventional photovoltaic materials. In this work, a large quantity of single-crystalline, orthorhombic phase Cu₄Bi ₄S₉ nanoribbons are fabricated using a facile solvothermal method. The growth of the Cu₄Bi₄S₉ nanoribbons is revealed to be a layer-by-layer stacking of Cu₄Bi ₄S₉ thin slabs via dodecylamine (DDA) linker, in which the number of stacking layers, and, subsequently, the width-to-thickness ratio, depends on the DDA concentration. Optical investigations show that the as-prepared Cu₄Bi₄S₉ nanoribbons have a narrow bandgap of E_g = 1.14 eV and enhanced surface photovoltage response in the entire visible wavelength range. It is indicated that these Cu ₄Bi₄S₉ nanoribbons have potential application in photodetectors, solar cells, or other optoelectronic devices.