Lead-free perovskite Rb2Sn1−xTexCl6 with bright luminescence for optical thermometry and tunable white light emitting diodes. Issue 36 (1st September 2022)

• Record Type: Journal Article
• Authors: Gong, Shunfa; Wu, Ruirui; Han, Qiuju; Kong, Degui; Wu, Wenzhi
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 36(2022)
• Page Start: 13217
• Page End: 13224
• Publication Date: 2022-09-01
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc02252d
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Te 4+ -doped Rb2 SnCl6 MCs are prepared by the solvothermal method, which have strong and broad emission. The long fluorescence lifetime and high PLQY make it have good application prospect in optical thermometry and white LED. Abstract : The low photoluminescence (PL) quantum yield (QY) of perovskite Rb2 SnCl6 severely limits its commercial development in optics, although it has perfect environmental stability and lead-free toxicity. Here, Te 4+ substituted lead-free double perovskite Rb2 SnCl6 microcrystals (MCs) are synthesized successfully by using the solvothermal method, which have a bright broad-band emission and large Stokes shift. The band gaps of Rb2 Sn1− x Te x Cl6 calculated by density functional theory (DFT) are close to the corresponding experimental band gaps. It is verified by DFT that partial Te 4+ substitution causes the Rb2 SnCl6 from the direct band gap to the indirect band gap. Temperature-dependent steady-state and time-resolved PL (TRPL) spectra as well as absorption spectra reveal that the broad-band emission at 560 nm is attributed to self-trapped excitons (STEs). Then, the PL lifetime of Rb2 Sn0.95 Te0.05 Cl6 MCs is first used to measure temperature in a wide temperature range. The maximum value of relative sensitivity ( S R ) obtained at the temperature from 355 to 370 K is 4.4% K −1, and the maximum value of absolute sensitivity ( S A ) obtained at 320 K is 28.23 ns K −1 from the calculation of the PL lifetime. PL lifetime measurements are not affected by sample size, excitation source power, and whether the luminous centers are uniformly distributed. The calculated data highlights the higher sensitivity optical thermometry of Rb2 Sn0.95 Te0.05 Cl6 MCs. Rb2 Sn0.95 Te0.05 Cl6 MCs combined with a commercial LED chip are successfully fabricated for the white light emitting diode (WLED). The correlated color temperature (CCT) of the WLED can be adjusted from 3582 to 5164 K by controlling the current. In summary, this research shows that Te 4+ substituted Rb2 SnCl6 double perovskite MCs exhibit great prospects in optical thermometry and tunable solid-state lighting.