Growth of wurtzite CuGaS2 nanoribbons and their photoelectrical properties

• Cu1.75S NCs play the catalytic roles for the growth of the CuGaS2 nanoribbon.
• During the growth of CuGaS2 nanoribbon, Cu1.75S NCs were consumed gradually.
• Photoresponse of CuGaS2 thin film shows 17-fold increase from dark to illumination.

We report on the growth of single crystalline wurtzite CuGaS2 nanoribbons by solution-based method. By investigating the evolutions of structure and composition during growth, it is confirmed that Cu1.75S nanocrystals play the catalytic roles for the formation and growth of the CuGaS2 nanoribbon. Derived from thermal decomposition of the copper precursor, the Cu1.75S nanocrystals formed firstly and were consumed gradually. When they exhausted, the growth of the nanoribbon stopped. Photoresponses of the CuGaS2 nanoribbons were evaluated by I–V curves based on CuGaS2 film fabricated by drop-casting method. The photocurrents of CuGaS2 film showed almost 17-fold increase in the dark than under illumination, indicating that the as-synthesized CuGaS2 nanoribbons are excellent photoactive materials for solar cell.