Achievement

IGERT Fellow Jonathan Choi and his collaborators fabricated solar cells using lead selenide nanocrystals that had the highest efficiencies to date for this material. Test devices had 3.35% efficiency -- much higher than previous record of 2% reported by the National Renewable Energy Laboratory. Lead selenide nanocrystals are promising candidates for next-generation solar cells due to their low cost and potentially high efficiency. Compared to conventional silicon-based solar cells, which have good efficiency but extremely high cost, nanocrystal-based devices should be economically viable for widespread deployment even at moderate efficiencies (~10%). Choi achieved his higher efficiencies by modifying the surface coatings on the nanocrystals, which improved the electronic properties of the devices. Understanding the effects of surface chemistry on charge transfer is an important, but often overlooked, goal, as all of the generated electricity must flow through these surfaces.