Yellow light emitting Cs2Zr0.99Te0.01Cl6 with high efficiency emission via modified co-precipitation method synthesis for the light-emitting device
While lead-free perovskite has attracted widespread interest in the optical field by overcoming their toxicity and stability disadvantages compared to conventional lead-based perovskite, the low photoluminescence quantum yield (PLQY) of lead-free perovskite has greatly limited their commercialization path. In this research, a modified co-precipitation method was used to prepare Cs 2 ZrCl 6 , which was achieved by the addition of TeCl 4 to shift the emission wavelength from 436 to 556 nm with bright yellow emission, the optimal PLQY of 98.2% was achieved by the addition of Te 4+ in the amount of 1 % and the optimization of the reaction concentration. First-principles calculations and spectral analysis of Cs 2 Zr 1-x Te x Cl 6 show that the broadband yellow light emission comes from self-trapped excitons (STEs) in Cs 2 Zr 1-x Te x Cl 6 . In addition, the luminous intensity of the prepared Cs 2 Zr 1-x Te x Cl 6 was 57.3, 63.3 and 90.1% of the initial intensity after exposure to air for 30 d, cyclic intermittent heating to 200°C and ultraviolet (UV) irradiation for 7 d, respectively. Finally, Cs 2 Zr 1-x Te x Cl 6 and Cs 2 ZrCl 6 :10% Bi were used as phosphors and encapsulated with a UV chip to make three different colors of light-emitting diodes (LED), where the white LED (WLED) had CIE coordinates of (0.3061 0.3244), color temperatures, color rendering indices as well as color tolerances of 6921 K, 84 and 6.52 respectively. This research provides a new approach to improve the performance of lead-free perovskite.
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