Optical properties of ytterbium-doped and undoped Cs₂AgInCl₆ thin films deposited by co-evaporation of chloride salts

Abstract

Ytterbium doped and undoped Cs2AgInCl6 films deposited by co-evaporation of metal halide salts luminesce in the visible and near infrared when excited with ultraviolet photons above its bandgap.

Stability of Cs2NaBiBr6 and Cs2NaBiCl6

“…We extract the band gap of 3.4 eV (∼365 nm) from the absorption of the Cs 2 NaBiCl 6 thin film, which is close to the calculated range of 3.4 to 3.7 eV for Cs 2 NaBiCl 6 . ,,, When excited at 360 nm, the Cs 2 NaBiCl 6 thin film exhibits a weak and broad emission centered at 700 nm (fwhm = 200 nm). This broad emission is also observed in single crystals and powders. ,, Due to the large Stokes shift, this broad emission at 700 nm is likely due to defects, though emission from self-trapped excitons has been suggested in similar materials. , …”

“… 16 , 19 , 23 Due to the large Stokes shift, this broad emission at 700 nm is likely due to defects, though emission from self-trapped excitons has been suggested in similar materials. 27 , 28 …”

“…16,19,23 Due to the large Stokes shift, this broad emission at 700 nm is likely due to defects, though emission from self-trapped excitons has been suggested in similar materials. 27,28 ■ CONCLUSIONS We coevaporated CsX, BiX 3 , and NaX (X = Cl, Br) stoichiometrically to yield Cs 2 NaBiBr 6 and Cs 2 NaBiCl 6 thin films. The Cs 2 NaBiBr 6 film appears unstable and forms a mixture of phases rather than the hypothesized cubic structure for double perovskites.…”