Realization of Tunable X‑ray Detection in 2D Chiral-Polar Hybrid Perovskites

Metal halide perovskites have emerged as outstanding
X-ray detection
absorption candidates, benefiting from their excellent carrier mobility,
strong radiation absorption capability, and ease of preparation. However,
the realization of highly anisotropic X-ray detection with a tunable
performance has rarely been investigated. Two-dimensional (2D) chiral-polar
hybrid perovskites with the natural multiple quantum wells (MQWs)
structure and the bulk photovoltaic effect (BPVE) present a prospective
solution to meet the requirement of highly anisotropic X-ray detection.
The pair of 2D chiral-polar perovskites has been synthesized in this
work, termed (R-β-MPA)PAPbI4 and (S-β-MPA)PAPbI4 (1R and 1S, MPA = methylphenethylamine
and PA = propylamine), aiming to achieve unique anisotropic X-ray
detection resulting from the coupling of the distinctive MQWs structure
and the BPVE. As expected, photodetectors based on high-quality single
crystals of 1R result in a high dichroism ratio (Imax/Imin ≈
7) for self-powered polarized-light detection. Strikingly, these photodetectors
achieve high anisotropic ratios, reaching up to 9 under X-ray irradiation.
This work reveals a strong correlation between X-ray detection performance
and the coupling of specially oriented crystals with the BPVE, opening
new possibilities for the realization of tunable X-ray detection.