Excitation-tailored dual-color emission of manganese(II)-doped perovskite nanocrystals

Abstract

Manganese(II)-doped perovskite nanocrystals with superior dual-color light emission properties are promising for optoelectronic applications. Here, we report that the emission color of these nanocrystals can be tailored by continuous-wave excitation because of the saturation of dopant emission at a record low light density ($10 mW/cm 2). By detuning the repetition rates of excitation laser sources, we show that the bottleneck of exciton-manganese(II) energy transfer caused by the imbalanced excitation and deexcitation of 4 T 1 states is the primary mechanism underlying the emission saturation properties. Such a dual-color luminescence tunable by weak excitation is promising for uses in potential applications such as luminescent solar concentrators, light intensity sensors, anti-counterfeit printing, and photo-switchable image markers.

Halide Perovskite Nanocrystal Emitters

“…The maximum PLQY of their best sample was about 27% with a Mn‐doping concentration of 1.3%, and the excited‐state decay of the Mn emission at 585 nm exhibited a long lifetime of about 1.4 ms, which is a typical timescale for Mn emission in d–d transition. [ 70 ] Ghosh et al and Wang et al nearly simultaneously reported the temperature‐dependent variation of emission intensity and emission wavelength of both host PNCs (CsPbCl 3 ) and Mn dopants ranging from tens of kelvin to more than 300 K. [ 71,72 ] They observed the blue shift of the emission peak position with the increasing temperature (Figure 3f,g), attributed to the interplay between the electron–phonon renormalization and the thermal expansion. Ghosh et al found that the PL intensity of Mn 2+ diminishes with the increasing temperature up to 125 K, due to the thermal quenching induced by the thermal ionization of optically excited carriers.…”

Untethered Microrobots for Active Drug Delivery: From Rational Design to Clinical Settings

“…Through the layer‐by‐layer assembly, multifunctional micromotors could be manufactured at micron size in an easy way, which provides more space for active micro‐design to meet different applications. [ 73 ] Biology in nature also provides excellent biomaterials for the design of microrobots. Xu et al.…”

“…As a natural active drug carrier, especially for diseases in the female reproductive tract, the sperm cells exhibited a high drug encapsulation capability and drug‐carrying stability, conveniently minimizing toxic side effects and unwanted drug accumulation in healthy tissues. [ 73 ]…”

“…The encapsulated drug was released by the sperm‐cancer membrane fusion when the micromotor hits the tumor wall. [ 73 ] Green microalga is another natural candidate for potential active DDS since its intrinsic morphology and perception properties, which could be well adopted for delivery process. [ 120 ] Microalgae‐based magnetic microswimmers have presented intrinsic helical templates, autofluorescence, MRI signals, cytotoxic effects toward cancer cell line, degradability for design, and low‐cost mass‐production of active DDS.…”

“…The sperm‐like micromotors trigger the release of DOX through the sperm‐cancer membrane fusion after hitting the tumor walls. [ 73 ] Followed by the intracellular uptake into tumor cells, the bacteria‐propelled DOX‐contained microrockets were triggered in response to acidic signals. [ 109 ] The mechanisms employed here could be further improved by the insights of intracellular drug delivery associated with surface properties, shape, and size, for advanced delivery efficiency.…”