Hot-injection synthesis of Co0.85Se nanocrystals for photo-electrical application

• Particulate shape Co0.85Se nanocrystals were synthesized by the hot-injection method.
• The Co0.85Se thin films prepared by drop-coating nanocrystals ink show an optical band gap value of 1.16 eV and remarkable photoresponse.
• Co0.85Se nanocrystals have great potential in photo-electrical conversion application.

Co0.85Se nanocrystals were synthesized via the hot-injection method using oleylamine (OLA) as solvent. The experimental results indicate that the reaction temperature plays an important role in the formation of Co0.85Se nanocrystals. Meanwhile, it is also found that the source of cobalt (CoCl2) should be excessive to obtain pure Co0.85Se nanocrystals. The obtained nanocrystals exhibit particulate shape and pure hexagonal Co0.85Se phase based on transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses. Optical and optoelectronic properties of the film drop-coated by Co0.85Se nanocrystals ink were also characterized. The obtained sample shows an optical band gap value of 1.16 eV and remarkable photo-electrical response, suggesting that the prepared Co0.85Se nanocrystals have the great potential in photo-electrical conversion application.