W-Doped Cs2SnCl6 for Near-Infrared Emission

Abstract

0D perovskite derivatives such as Cs2WCl6 and Cs2WOxCl6–x have been recently shown to emit near-infrared (NIR) radiation. The d–d electronic transition of W4+/W5+ yields an NIR emission. However, the close proximity of those ions can quench the photoluminescence via concentration quenching. To address this issue, here we dilute the emission centers by doping a small amount of W into the Cs2SnCl6 0D perovskite. The results suggest that the dopant centers are [WOCl5]2– replacing [SnCl6]2– octahedra in the host lattice. The optimal 3.3% W-doped Cs2SnCl6 exhibits NIR (965 nm) emission with over 52 times higher intensity compared to that of Cs2WOxCl6–x. The suppression of concentration quenching in W-doped Cs2SnCl6 also significantly alters its temperature-dependent (7–300 K) photoluminescence compared to that of Cs2WOxCl6–x. Finally, we demonstrated NIR phosphor-converted light-emitting diodes of W-doped Cs2SnCl6 showing an output power of 10.3 mW at 400 mA. This is the first report of W doping in 0D perovskites showing its potential as an NIR phosphor.