Lead-free halide perovskites have been developed and have received increasing attention in optoelectronic applications due to their non-toxicity. However, single perovskite phosphors that emit vibrant, tunable-color-temperature white-light are rare. Herein, we used the anti-solvent precipitation method to develop white light-emitting diodes (WLEDs) based on rare-earth-based Sb3+ and Mn2+ co-doped Cs2KYCl6 microcrystals (MCs). The Cs2KYCl6 MCs exhibit tunable dual emissions covering a wideband ascribed to the emission of self-trapped excitons (STEs) from Sb3+ and the 4T1 to 6A1d–d transition of Mn2+. The optimal photoluminescence quantum yield (PLQY) of doped Cs2KYCl6 is 65.78%. The energy transfer process from Sb3+ to Mn2+ is revealed. WLEDs have been successfully constructed by combining the dual emissions from STEs of Sb3+ and the d–d transition of Mn2+. These WLEDs demonstrate impressive optical performance, including CIE chromaticity coordinates (0.3483, 0.4125) and a color rendering index (CRI) of 85.4. This work provides an effective strategy for developing WLEDs based on a single-component material, lead-free perovskites.
Yongrun Dong,Wen Li,Tao Huang,Shuaigang Ge,Linghang Kong,Chuang Ning,Zequan Li,Wei Gao,Bingsuo Zou
Recently, lead-free double perovskites have been regarded as a promising alternative to lead halide perovskites due to their wide emission band, and environmental protection and stability properties, and are expected to become a series of rising star materials in the lighting field. However, currently, the growth of most lead-free double perovskites occurs in the strong acid environment, which not only brings high cost and environment risk, but also makes it hard to realize large-scale applications with powder products. Herein, we apply a strategy of in situ synthesis of lead-free double perovskites in a polymer matrix by using a small amount of precursors and relatively friendly DMSO solvent to obtain efficiently luminescent Sb3+/Mn2+ co-doped Cs2KInCl6/PVDF composite films in a large-area. The co-doping of Mn2+/Sb3+ into this inorganic double perovskite matrix makes microcrystals with good crystallinity and size distribution in this polymer. The as prepared co-doping composite film with Mn/Sb feeding ratio 16 : 1 shows the brightest white light emission under 320 nm excitation, with a photoluminescence quantum yield (PLQY) as high as 86.98%. The energy transfer (E-T) from the charge-transfer band to the triplet self-trapped exciton (STE) around Sb3+ and then to the ferromagnetic (FM) coupled Mn2+ pair 3d state was confirmed by the temperature-dependent PL spectra and density functional theory calculations. Finally, a single-compound white light emitting diode with chromatic coordinates of (0.31, 0.33) and fluorescent anti-counterfeiting labels could be fabricated based on this composite film with the best white emission. This work provides a new strategy for the application of lead-free double perovskites in the fields of lighting and anti-counterfeiting.
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