Achievement

IGERT Fellow David Stachnik and collaborators have fabricated a new type of solar cell based on nanocrystals of lead sulfide (PbS) and nickel oxide (NiO). Solar cells use light to transfer charge across an interface between an n- and a p-type semiconductor, thereby generating electricity. Lead sulfide, an n-type semiconductor, absorbs light very effectively. The problem is that most p-type semiconductors suitable for pairing with PbS are organic materials with limited long-term stability. Stachnik and coworkers used optical techniques to show that charge flows rapidly across the interface between PbS and NiO, an inorganic p-type semiconductor. Buoyed by these results, Stachnik fabricated solar cells using NiO and PbS nanocrystals. Initial devices had efficiencies up to 3% which is comparable to solar cells with organic hole-transporting layers. This new design may lead to low-cost, all-inorganic solar cells that are efficient and long-lasting.