Abstract:
Bismuth-based perovskites are attracting intense scientific interest due to low
toxicity and excellent moisture stability compared to lead-based analogues. However, high
exciton binding energy, poor charge carrier separation, and transport efficiencies lower their
optoelectronic performances. To address these issues, we have integrated an electronically
active organic cation, naphthalimide ethylammonium, between the [BiI5
2−]n chains via
crystal engineering to form a novel perovskite-like material (naphthalimide ethylammonium)
2BiI5 (NBI). Single crystal analysis revealed a one-dimensional quantum-well
structure for NBI in which inter-inorganic well electronic coupling is screened by organic
layers. It exhibited anisotropic photoconductivity and long-lived charge carriers with
milliseconds lifetime, which is higher than that of CH3NH3PbI3. Density functional theory
calculations confirmed type-IIa band alignment between organic cations and inorganic
chains, allowing the former to electronically contribute to the overall charge transport
properties of the material.
