Polarization surface-charge density of single semiconductor quantum rods

Electrostatic force microscopy was used to determine that single CdSe quantum rods (QRs) have a permanent polarization surface-charge density, an unexpected observation for supposedly well-shaped particles. The surface charge results from a slight angle between the QR sides and the direction of internal electric polarization. By contrast, despite the large dipole moment expected for CdSe QRs, none was observed. The unavoidable presence of permanently charged surfaces on CdSe QRs has the potential to impede the development of novel devices incorporating these materials.