Solar cells based on junctions between colloidal PbSe nanocrystals and thin ZnO films.

We report a new type of excitonic solar cell based on planar heterojunctions between PbSe semiconductor nanocrystals and thin ZnO films. These solar cells generate large photocurrents and higher photovoltages compared to Schottky cells assembled with similar nanocrystal films. When illuminated with 100 mW/cm(2) simulated AM1.5 spectrum, these solar cells exhibit short-circuit currents between 12 and 15 mA/cm(2), open-circuit voltages up to 0.45 V, and a power conversion efficiency of 1.6%. The photovoltage depends on the size of the nanocrystals, increasing linearly with their effective band gap energy.