Credit: Image courtesy of Yuri Dahnovsky
One approach for solar cells uses quantum dots only tens of atoms across to absorb the sunlight and convert it into electricity. Scientists have shown that replacing a few of the lead atoms in a lead sulfide (PbS) quantum dot with manganese (Mn) can greatly improve the efficiency of the conversion. The image shows the overlap of the atomic orbitals (grey shaded regions) between the quantum dot and first atomic layers of the balance of the solar cell (zinc tin oxide, ZnO-SnO2). The overlap of the orbitals is enhanced when lead (Pb) is replaced with Mn, resulting in faster movement of the electrons from the quantum dot.