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Nanotechnology ; 31(6): 065603, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31645023


White light-emitting diodes (WLEDs) based on all-inorganic perovskite CsPbX3 (X = Cl, Br, I) quantum dots (QDs) have attracted much attention and rely on mixing several colors of perovskites. However, this inevitably leads to a non-uniform light distribution and serious light loss. Here, a novel strategy was demonstrated to obtain white emission by combining the orange and blue emission from CsPb/Mn(Cl/Br)3 QDs. Notably, highly efficient white emission with a photoluminescence quantum yield of 94% was achieved by an anion exchange surface engineering (AESE) strategy. After AESE treatment the surface traps can be eliminated, resulting in improved exciton and Mn2+ emission. A prototype WLED device was fabricated and exhibited excellent optical stability, demonstrating great potential for perovskite QDs in the field of optoelectronics.

ACS Appl Mater Interfaces ; 11(37): 34109-34116, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31441301


Lead halide perovskites are emerging as promising candidates for high-efficiency light-emitting diode (LED) applications because of their tunable band gaps and high quantum yield (QY). However, it remains a challenge to obtain stable red emitting materials with high QY. Herein, we report a facile and convenient hot-injection strategy to synthesize Mn-doped two-dimensional (2D) perovskite nanosheets. The emission peak can be tuned from 597 to 658 nm by manipulating the crystal field strength. In particular, a QY as high as 97% for 2D perovskite is achieved. The as-prepared perovskite also possesses excellent stability, whose emission property can be maintained for almost one year. A monochrome LED is further fabricated by employing the as-prepared perovskite as phosphor, which also shows high long-term stability. We believe that these highly efficient and stable perovskites will open up new opportunities in LED applications.

Nanoscale Res Lett ; 14(1): 152, 2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-31049739


Perovskite quantum dots (QDs) have been widely used in white light-emitting diodes (WLEDs), due to their high quantum yield (QY), tunable bandgap, and simple preparation. However, the red-emitting perovskite QDs are usually containing iodine (I), which is not stable under continuous light irradiation. Herein, perovskite-based WLED is fabricated by lead-free bismuth (Bi)-doped inorganic perovskites Cs2SnCl6 and less-lead Mn-doped CsPbCl3 QDs, which emits white light with color coordinates of (0.334, 0.297). The Bi-doped Cs2SnCl6 and Mn-doped CsPbCl3 QDs both show excellent stability when kept in the ambient air. As benefits from this desired characteristic, the as-prepared WLED shows excellent stability along with operating time. These results can promote the application of inorganic perovskite QDs in the field of WLEDs.

ACS Appl Mater Interfaces ; 11(8): 8210-8216, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30719905


For data security applications, the use of fluorescent inks has become the most promising approach because of their convenience and low cost. However, traditional fluorescent inks are usually visible either under ambient light or UV light, whereas the improved stimuli-responsive inks are restricted to a single color. For the first time, full-color stimuli-responsive inks for information coding, encryption, and decryption are reported, which rely on the facile preparation and conversion of perovskite quantum dots. The information printed by the halide salt solution is invisible under ambient and UV light but becomes readable under UV light after spraying a unique developer. Besides, the primitive information can be stored for many years, even decades. Even after the decryption process, it still can be stored for at least several weeks. Most importantly, using butyl amine and acetic acid as encryption and decryption reagents, respectively, can switch off/on the luminescence. In this way, the printed information can be encrypted and decrypted, which shows great potential for information security applications.

Nanotechnology ; 30(24): 245201, 2019 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-30812014


CsPbX3 perovskite nanocrystals (NCs) are becoming a promising material for optoelectronic devices that possess an optically tunable bandgap, and bright photoluminescence. However, the toxic Pb is not environmentally friendly and the quantum yield (QY) of blue emitting NCs is relatively low. In addition, the red emitting perovskite containing iodine is not stable under light illumination. In this paper, high QY, blue emitting, non-toxic fluorescent nanomaterial carbon dots and orange-emitting CsPb0.81Mn0.19Cl3 NCs with partial Pb replacement are combined to fabricate white light-emitting diodes (WLEDs). A WLED with color coordinates of (0.337, 0.324) and a correlated color temperature of 4804 K is fabricated. Compared to red emitting perovskite containing iodine, the CsPb0.81Mn0.19Cl3 NCs are stable no matter whether they are stored in the air or exposed under ultraviolet light. Therefore, the as-fabricated WLED shows good color stability against increasing currents and long-term working stability.