Photovoltaic devices with depleted heterojunctions and shell-passivated nanoparticles

A photoelectric device comprising:

• a light-transmitting first electrode;
• a first semiconductor layer in direct electrical contact with the first electrode;
• a second semiconductor layer in direct electrical contact with the first semiconductor layer and comprising light-absorbing nanoparticles, wherein each of the nanoparticles comprises a quantum dot core comprising a single quantum dot and surface anions, a first shell comprising cations bound to the surface anions of the quantum dot core, and a second shell comprising anions bound to the cations, wherein the nanoparticles are not passivated by organic ligands, and wherein the anions of the second shell are a member selected from the group consisting of halogen ions and thiocyanate ion;
• and
• a second electrode in direct electrical contact with the second semiconductor layer.

A method of forming passivated p-type semiconductor nanoparticles, the method comprising:

• treating p-type semiconductor colloidal quantum dots having surface anions with a solution of a cation-containing reagent that passivates the surface anions to form colloidal quantum dots coated with the cations, and
• treating the colloidal quantum dots with a solution of an anion-containing reagent that passivates the cations,
• wherein the forming passivated p-type semiconductor nanoparticles are not passivated by organic ligands;
• and
• wherein the anion of the anion-containing reagent is a member selected from the group consisting of halogen ions and thiocyanate ion.