Two-dimensional hybrid-organic–inorganic perovskite
(2D-HOIP)
lead bromide perovskite crystals have demonstrated great potential
as scintillators with high light yields and fast decay times while
also being low cost with solution-processable materials for wide energy
radiation detection. Ion doping has been also shown to be a very promising
avenue for improvements of the scintillation properties of 2D-HOIP
crystals. In this paper, we discuss the effect of rubidium (Rb) doping
on two previously reported 2D-HOIP single crystals, BA2PbBr4and PEA2PbBr4. We observe
that doping the perovskite crystals with Rb ions leads to an expansion
of the crystal lattices of the materials, which also leads to narrowing
of band gaps down to 84% of the pure compounds. Rb doping of BA2PbBr4and PEA2PbBr4shows
a broadening in the photoluminescence and scintillation emissions
of both perovskite crystals. Rb doping also leads to faster γ-ray
scintillation decay times, as fast as 4.4 ns, with average decay time
decreases of 15% and 8% for Rb-doped BA2PbBr4and PEA2PbBr4, respectively, compared to those
of undoped crystals. The inclusion of Rb ions also leads to a slightly
longer afterglow, with residual scintillation still being below 1%
after 5 s at 10 K, for both undoped and Rb-doped perovskite crystals.
The light yield of both perovskites is significantly increased by
Rb doping with improvements of 58% and 25% for BA2PbBr4and PEA2PbBr4, respectively. This work
shows that Rb doping leads to a significant enhancement of the 2D-HOIP
crystal performance, which is of particular significance for high
light yield and fast timing applications, such as photon counting
or positron emission tomography.