posted on 2023-12-07, 21:24authored byAlexander
M. Oddo, Mengyu Gao, Daniel Weinberg, Jianbo Jin, Maria C. Folgueras, Chengyu Song, Colin Ophus, Tomoyasu Mani, Eran Rabani, Peidong Yang
Energy funneling is a phenomenon
that has been exploited
in optoelectronic
devices based on low-dimensional materials to improve their performance.
Here, we introduce a new class of two-dimensional semiconductor, characterized
by multiple regions of varying thickness in a single confined nanostructure
with homogeneous composition. This “noninteger 2D semiconductor”
was prepared via the structural transformation of two-octahedron-layer-thick
(n = 2) 2D cesium lead bromide perovskite nanosheets;
it consisted of a central n = 2 region surrounded
by edge-lying n = 3 regions, as imaged by electron
microscopy. Thicker noninteger 2D CsPbBr3 nanostructures
were obtained as well. These noninteger 2D perovskites formed a laterally
coupled quantum well band alignment with virtually no strain at the
interface and no dielectric barrier, across which unprecedented intramaterial
funneling of the photoexcitation energy was observed from the thin
to the thick regions using time-resolved absorption and photoluminescence
spectroscopy.