Eliminating emissive sub-bandgap states in nanocrystals
AssigneeMassachusetts Institute of Technology
InventorsGyuweon Hwang, Donghun Kim, Jose M. Cordero, Mark W. B. Wilson, Chia-Hao M. Chuang, Jeffrey C. Grossman, Moungi G. Bawendi
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Abstract
The size-dependent band-gap tunability and solution processability of nanocrystals (NCs) make them attractive candidates for optoelectronic applications. One factor that presently limits the device performance of NC thin films is sub-bandgap states, also referred to as trap states. Trap states can be controlled by surface treatment of the nanocrystals.
Claims19
A method of modifying a surface of nanocrystal including contacting a surface of the nanocrystal with an oxidizing agent, wherein the nanocrystal is a Group II-VI compound, a Group II-V compound, a Group III-VI compound, a Group III-V compound, a Group IV-VI compound, a Group I-III-VI compound, a Group II-IV-VI compound, or a Group II-IV-V compound,
- treating the surface with the oxidizing agent until a density of trap states for the nanocrystal having the oxidized surface compared to the nanocrystal having an untreated surface is reduced by at least 20-fold and
- removing under-charged atoms on the surface.
A method of treating a film that includes nanocrystal comprising contacting a surface of the nanocrystal with an oxidizing agent, wherein the nanocrystal is a Group II-VI compound, a Group II-V compound, a Group III-VI compound, a Group III-V compound, a Group IV-VI compound, a Group I-III-VI compound, a Group II-IV-VI compound, or a Group II-IV-V compound,
- forming a modified surface in which a density of trap states for the nanocrystal having the oxidized surface compared to the nanocrystal having an untreated surface is reduced by at least 20-fold and
- removing under-charged atoms on the film with the oxidizing agent.
Dependencies are inferred from the claim text.