Efficient Charge Transport in Zero-Dimensional Perovskite for Ultrahigh-Sensitivity X-Ray Detection

Traditional 0D Bi-based perovskites suffer from inherently poor charge transport, limiting their application in X-ray detection. Here, we report a molecularly engineered 0D compound, Dpy 3 Bi 2 I 12 , featuring conjugated dipyridine cations at the A-site that enhance hydrogen bonding within [BiI 6 ] 3− octahedra and promote the formation of a quasi-2D framework. Compared to conventional MA 3 Bi 2 I 9 , this design shifts the Fermi level closer to the conduction band (CB), enabling more efficient electron injection, as evidenced by ultrafast transient absorption spectroscopy and partial density of states calculations that reveal efficient carrier generation and delocalization between iodide octahedra and conjugated ligands, thereby overcoming the intrinsic confinement of 0D lattices. As a result, Dpy 3 Bi 2 I 12 achieves an ultralow detection limit of 4.4 nGy s −1 , a high sensitivity of 10,600µC·Gy −1 cm −2 at a low operating bias of −5 V·mm −1 . These findings demonstrate an effective strategy for unlocking efficient charge transport in 0D perovskites, advancing their prospects for low-dose, high-resolution X-ray imaging.