Preparation and photo-induced charge transfer of the composites based on branched CdS nanocrystals and PCPDTBT

Abstract

Rich branched CdS nanocrystals were synthesized by a facile hydrothermal treatment from Cd(NO3)2, thiourea and hexamethylenetetramine [(CH2)6N4, HMT], where HMT acted as a capping agent. The morphology, structure and phase composition of CdS nanostructures were examined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and high-resolution TEM. The composites based on CdS nanocrystals and Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b:3,4-b’]dithiophene-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) have been prepared by mixing of the two components in chloroform. The optical properties of the composites are investigated using ultraviolet–visible (UV–Vis) absorption and photoluminescence (PL) spectroscopies. A significant fluorescence quenching of PCPDTBT in the composites is observed at high CdS nanocrystals/PCPDTBT ratios, indicating that the photo-induced charge transfer occurred due to the energy level offset between the donor PCPDTBT and the acceptor CdS nanocrystals.