Modulating Luminescence of Double Perovskites by Intrinsic Strain Effect and Applications in White Light Emitting Devices

Double perovskite (DP) is considered as a promising candidate for single-component white-light emitters. However, the photoluminescence (PL) efficiency of the small sized DP, such as microcrystals and nanocrystals, is generally unsatisfactory. In this work, by comparing the Sb/Bi co-doped Cs 2 NaInCl 6 microcrystals prepared at different conditions, it is revealed that the PL spectral profile and efficiency are highly dependent on intrinsic strain effect. All the Sb/Bi co-doped Cs 2 NaInCl 6 DPs exhibit blue PL at ≈445 nm and yellow PL at ≈560 nm. When the crystal size decreases, the release of local strain results in a significant quenching in the emission intensity. Accordingly, by optimizing the reaction conditions to introduce sufficient lattice mismatch, high PL quantum yields (QYs) of 76.38% and 86.44% are obtained for blue and yellow PL, respectively. Moreover, a white light-emitting convertor with a high colour rendering index (CRI) of 90.0 is fabricated, which shows a luminous efficiency of 40.4 lm W −1 .