  Due to their excellent optical and electrical properties as well as versatile
growth and fabrication processes, lead halide perovskites have been widely
considered as promising candidates for green energy and opto-electronic related
applications. Here, we investigate their potential applications at infrared
wavelengths by modeling the intersubband transitions in lead halide
perovskite-based quantum well systems. Both single-well and double-well
structures are studied and their energy levels as well as the corresponding
wavefunctions and intersubband transition energies are calculated by solving
the one-dimensional Schr\"odinger equations. By adjusting the quantum well and
barrier thicknesses, we are able to tune the intersubband transition energies
to cover a broad range of infrared wavelengths. We also find that the
lead-halide perovskite-based quantum wells possess high absorption
coefficients, which are beneficial for their potential applications in infrared
photodetectors. The widely tunable transition energies and high absorption
coefficients of the perovskite-based quantum well systems, combined with their
unique material and electrical properties, may enable an alternative material
system for the development of infrared photodetectors.
