Seeded growth of HgTe nanocrystals for shape control and their use in narrow infrared electroluminescence
Résumé
HgTe colloidal nanocrystals (NCs) have become a promising building block for infrared optoelectronics. Despite their cubic zinc blende lattice, HgTe NCs tend to grow in a multipodic fashion, leading to poor shape and size control. Strategies to obtain HgTe NCs with well-controlled sizes and shapes remain limited and sometimes challenging to handle, increasing the need for a new growth process. Here, we explore a synthetic route via seeded growth. In this approach, the small HgTe seeds are nucleated in the first step, and they show narrow and bright photoluminescence with 75% quantum yield in the near infrared region. Once integrated into Light emitting diodes (LEDs), these seeds lead to devices with high radiance up to 20 WSr-1 m-2 and a long lifetime. Heating HgTe seeds formed at the early stage leads to the formation of sphere-shaped HgTe with tunable band edges from 2 to 4 µm. Last, the electronic transport tests conducted on sphere-shaped HgTe NC arrays reveals enhanced mobility and stronger temperature dependence than the multipodic shaped particles.
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