Facile synthesis of CdSe nanocrystals for bulk-heterojunction solar cells

Oleic acid (OA)-capped cadmium selenide (CdSe) nanocrystals (NCs) have been synthesized via a new high-scale route. X-ray diffraction and transmission electron microscopy confirmed that rod-like hexagonal (wurtzite) CdSe NCs with an average size of 10 nm were obtained via this new route. The obtained CdSe NCs were treated individually with pyridine and tert-butylamine (t-BA) for ligand exchange. Fourier transform infrared spectra of the as-synthesized and treated CdSe NCs confirmed the removal of OA ligands from the surface of CdSe NCs after treatments with pyridine and t-BA. Bulk-heterojunction (BHJ) solar cell devices were prepared using untreated and surface treated CdSe NCs blended with poly (3-hexylthiophene-2,5-diyl) (P3HT) polymer. BHJ solar cell devices made from P3HT:(surface treated CdSe NCs) blends showed greater improvement in photovoltaic performances compared to P3HT:(untreated CdSe NCs) blend. The improvement in photovoltaic performances was due to the increase of electron mobility in P3HT:(CdSe NCs) blends after surface treatment of CdSe NCs.