Perovskite
and chalcogenide quantum dots (QDs) are important nano
semiconductors. It has been a challenge to synthesize heterostructural
QDs combining perovskite and chalcogenide with tailorable photoelectronic
properties. In this report, heterostructural CsPbX3-PbS
(X = Cl, Br, I) QDs were successfully synthesized via a room temperature
in situ transformation route. The CsPbX3-PbS QDs show a
tunable dual emission feature with the visible and near-infrared (NIR)
photoluminescence (PL) corresponding to CsPbX3 and PbS,
respectively. Typically, the formation and evolution of the heterostructural
CsPbBr3–PbS QDs with reaction time was investigated.
Femtosecond transient absorption spectroscopy (TAS) was applied to
illuminate the exciton dynamics in CsPbBr3–PbS QDs.
The mild synthetic method and TAS proved perovskite to PbS energy
transfer may pave the way toward highly efficient QD photovoltaic
and optoelectronic devices.
Combining inorganic perovskite quantum dots (IPQDs) devices with Si platform is an interesting topic since it is helpful for realizing the optoelectronic integration as well as the multiple‐functional electronics in a compact and lightweight format. However, the poor energy band alignment between the IPQDs and Si limits the device performance, such as the emitting efficiency. Here, a light‐emitting diodes (LEDs) structure is proposed by inserting a poly‐TPD (poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)‐benzidine]) layer between the n‐type IPQDs and the p‐type Si substrate. The light‐emitting diode based on CsPbI3 quantum dots reaches an output power density of 1.68 mW cm−2 with external quantum efficiency of 0.91%, which is enhanced by 34‐fold compared with the reference device. Similar emission enhancement is also observed in the device based on CsPbBr3 quantum dots but the output power density is only 0.6 mW cm−2. In order to further improve the emission intensity of CsPbBr3 quantum dots devices, Au nanoparticals (Au NPs) are introduced into the hole injection layer, the output power density increases to 1.2 mW cm−2, which is induced by the localized surface plasmon resonance coupling between Au NPs and CsPbBr3 excitons. The results demonstrate that high‐efficiency and stable Si‐based perovskite LEDs can be realized by rational optical and electronic design.
Inorganic perovskites have emerged as a promising candidate for light-emitting devices due to their high stability and tunable band gap. However, the power consumption and brightness have always been an issue for perovskite light-emitting diodes (PeLEDs). Here, we improved the luminescence intensity and decreased the current density of the PeLEDs based on CsPbI3 quantum dots (QDs) and p-type Si substrate through an alternating current (AC) driving mode. For the different driving voltage modes (under a sine pulsed bias or square pulsed bias), a frequency-dependent electroluminescent (EL) behavior was observed. The devices under a square pulsed bias present a stronger EL intensity under the same voltage due to less thermal degradation at the interface. The red PeLEDs under a square pulsed bias driving demonstrate that the EL intensity drop-off phenomenon was further improved, and the integrated EL intensity shows the almost linear increase with the increasing driving voltage above 8.5 V. Additionally, compared to the direct current (DC) driving mode, the red PeLEDs under the AC condition exhibit higher operating stability, which is mainly due to the reducing accumulated charges in the devices. Our work provides an effective approach for obtaining strong brightness, low power consumption, and high stability light-emitting devices, which will exert a profound influence on coupling LEDs with household power supplies directly.
Antimony nanocrystals (Sb NCs) are of interest in energy storage, catalysis and cancer therapy for its special physical, chemical and biomedical properties. However, methodology challenges still remain in preparation of colloidal Sb NCs, due to the restricted reaction solution systems, high temperature and time costing for common routes. Herein, size controllable colloidal Sb NCs were continuously prepared by pulsed laser ablation of Sb target in different solvents, owning to the metal nanodroplet explosive ejection and thermal evaporation mechanisms. These well dispersed and stable Sb NCs showed excellent photothermal property in the near-infrared-II window.
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