Ligand-Engineered HgTe Colloidal Quantum Dot Solids for Infrared Photodetectors

HgTe colloidal quantum dots (CQDs) arepromising absorber systems for infrared detection due to theirwidely tunable photoresponse in all infrared regions. Up to now,the best-performing HgTe CQD photodetectors have relied onusing aggregated CQDs, limiting the device design, uniformity andperformance. Herein, we report a ligand-engineered approach thatproduces well-separated HgTe CQDs. The present strategyfirstemploys strong-binding alkyl thioalcohol ligands to enable thesynthesis of well-dispersed HgTe cores, followed by a secondgrowth process and afinal postligand modification step enhancingtheir colloidal stability. We demonstrate highly monodisperseHgTe CQDs in a wide size range, from 4.2 to 15.0 nm with sharp excitonic absorption fully covering short- and midwave infraredregions, together with a record electron mobility of up to 18.4 cm2V-1s-1. The photodetectors show a room-temperature detectivityof 3.9x1011jones at a 1.7 mu m cutoffabsorption edge