Copper antimony sulfide nanoparticles applied to solar cells

Full text: Due to their optical properties, some semiconductor nanoparticles have been applied as sensitizers for harvesting solar energy. Unfortunately, the most efficient and widely used materials present either cadmium, lead or indium in their composition, making them expensive or toxic. Hence, the development of efficient yet environmentally friendly and low-cost sensitizers is crucial to scale up the production of solar cells. The aim of this work is to synthesize copper antimony sulfide (CuxSbySz) nanoparticles and to evaluate their potential as a solar harvesting material. Briefly, in a three-neck flask, copper (I) chloride, antimony (III) chloride and oleylamine (OLA) were added and heated to the synthesis temperature (200 to 250 °C). In another flask, sulfur and OLA were added, heated to 60 °C, and stirred until the dissolution of the sulfur. This solution was injected in the three-neck flask and the reaction was allowed for different periods (from 1 to 10 minutes). The optically active layer of CuxSbySz nanoparticles was deposited over a mesoporous TiO2 layer, and the device was assembled with a counter electrode of platinum nanoparticles and an electrolyte (40 mM solution of a redox pair 3I-/I3 -). X-ray diffractograms and Raman spectra showed the formation of Cu₃SbS₄ and CuSbS₂. The TEM images showed the formation of nanoparticles with diameter between 15 and 43 nm. The optical bandgap obtained through the Tauc plot, presented values between 0.98 and 1.63 eV. The solar cells sensitized with these materials presented efficiencies between 0.007 and 0.054%. Despite the low efficiency values, the results are very promising and the samples will be morphologically and structurally improved to enhance this performance. (author)