posted on 2022-12-29, 15:03authored byManman Gong, Fei Li, Lei Wang, Qiulei Xu, Zhenghui Wu, Huaibin Shen, Lin Song Li, Zuliang Du
Solution-processed PbS quantum dot light-emitting diodes
(QLEDs)
with emission in the second near-infrared window (NIR-II, 1100–1700
nm) are excellent candidates as light sources for optical communication,
night vision, and biomedical monitoring. However, it is still a tremendous
challenge to achieve high-radiance PbS QLEDs due to serious QD surface
traps and unbalanced charge injection. Herein, highly monodisperse
PbS QDs with tailored facet growth were successfully synthesized by
the continuous precursor injection method. The synthesized PbS QDs
revealed a tunable absorption peak from 1200 to 1700 nm with a supernarrow
full width at half-maximum (fwhm; <105 nm). The tailored surface
facet growth effectively decreased the nonpolar (100) facet and surface
defects. Furthermore, with a multilayered organic–inorganic
hybrid architecture of indium tin oxide (ITO)/poly(ethylenedioxythiophene):polystyrenesulfonate
(PEDOT:PSS)/poly(9,9-dioctylfluorene-co-N-(4-(3-methylpropyl))-diphenylamine) (TFB)/PbS QDs/ZnO/Al, the novel
infrared PbS QLED exhibited an excellent maximum radiance of 16.14
W sr–1 m–2 at 6.15 V with a shortwave-infrared
electroluminescence at ∼1530 nm. Importantly, the NIR-II QLEDs
using facet-tailored PbS QDs with the EL peak between 1100 and 1700
nm represented extremely high radiances. The excellent performances
are ascribed to the passivated PbS QDs with a tailored surface facet
and the hybrid device structure for charge injection balance. This
work provides an effective approach for the preparation of high-quality
PbS QDs and is expected to significantly boost the potential commercial
applications of PbS NIR-II QLEDs.