Undoped and Tl-doped Cs${}_3$Cu${}_2$I${}_5$ thin films as potential X-ray scintillators

0D halide perovskite Cs${}_3$Cu${}_2$I${}_5$-based nanocrystals and bulk crystals are proven to be sensitive and efficient scintillators for X-ray and $\gamma$-ray detection. Herein, undoped and Tl-doped Cs${}_3$Cu${}_2$I${}_5$ microcrystalline films are synthesized by a thermal evaporation method. Both films crystallize into a Pnma space group of orthorhombic crystal lattice with preferred (004) growth orientation. The undoped Cs${}_3$Cu${}_2$I${}_5$ thin film shows a sole emission peaking at 440 nm associated with the self-trapped exciton emission. Doping of Tl${}^{+}$ ions introduces another emission that peaks at 520 nm. The scintillation efficiency of both undoped and Tl-doped Cs${}_3$Cu${}_2$I${}_5$ thin films is about one-third of that of CsI:Tl thin film with the same size and thickness. Within the first 5 s after X-ray cutoff, afterglow signals of both the undoped and Tl-doped Cs${}_3$Cu${}_2$I${}_5$ thin films are over one order of magnitude lower than that of CsI:Tl thin film. (© 2021 Wiley‐VCH GmbH)