Law group has a new atomic layer deposition technique to make high-performance nanocrystal films for transistors and solar cells.
The fabrication of practical electronic devices based on nanocrystal solids depends on preventing oxidation, surface diffusion, ripening, sintering, and other unwanted physicochemical changes that can plague these materials. In a collaboration with NREL, the Law group has used low-temperature atomic layer deposition (ALD) to infill conductive lead selenide (PbSe) nanocrystal solids with metal oxides to produce inorganic nanocomposites in which the nanocrystals are locked in place and protected against oxidative and photothermal damage. Infilling nanocrystal field-effect transistors and solar cells with amorphous alumina yields devices that operate with enhanced and stable performance for at least months in air. Furthermore, ALD infilling with ZnO lowers the height of the inter-nanocrystal tunnel barrier for electron transport, yielding PbSe nanocrystal films with high electron mobilities. This ALD technique is a versatile means to fabricate robust nanocrystal solids for optoelectronic devices.