Quantum-well (QW) hybrid organic–inorganic perovskite
(HOIP)
crystals, e.g., A2PbX4(A = BA, PEA; X = Br,
I), demonstrated significant potentials as scintillating materials
for wide energy radiation detection compared to their individual three-dimensional
(3D) counterparts, e.g., BPbX3(B = MA). Inserting 3D into
QW structures resulted in new structures, namely A2BPb2X7perovskite crystals, and they may have promising
optical and scintillation properties toward higher mass density and
fast timing scintillators. In this article, we investigate the crystal
structure as well as optical and scintillation properties of iodide-based
QW HOIP crystals, A2PbI4and A2MAPb2I7. A2PbI4crystals exhibit
green and red emission with the fastest PL decay time <1 ns, while
A2MAPb2I7crystals exhibit a high
mass density of >3.0 g/cm3and tunable smaller bandgaps
<2.1 eV resulting from quantum and dielectric confinement. We observe
that A2PbI4and PEA2MAPb2I7show emission under X- and γ-ray excitations.
We further observe that some QW HOIP iodide scintillators exhibit
shorter radiation absorption lengths (∼3 cm at 511 keV) and
faster scintillation decay time components (∼0.5 ns) compared
to those of QW HOIP bromide scintillators. Finally, we investigate
the light yields of iodide-based QW HOIP crystals at 10 K (∼10
photons/keV), while at room temperature they still show pulse height
spectra with light yields between 1 and 2 photons/keV, which is still
>5 times lower than those for bromides. The lower light yields
can
be the drawbacks of iodide-based QW HOIP scintillators, but the promising
high mass density and decay time results of our study can provide
the right pathway for further improvements toward fast-timing applications.