Synergistic Effect of Chirality and Symmetry Reduction Enables Metal-Free Perovskite Single Crystal With Stable...

Exploring chiral components to induce a significant bulk photovoltaic effect (BPVE) for pursuing controllable dark current and device stability represents an effective avenue in metal-free perovskite (MFP) X-ray detection. However, the key challenges of increasing total polarization degree in the MFPs with complex hydrogen-bond networks retard the construction of stable self-driven X-ray detection. Herein, we designed a novel R/S-2MPAZE-NH₄I₃·H₂O SCs with right- or left-handed screw conformations through incorporating chiral cations of R/S-2MPAZE²⁺ for stable self-driven MFPs-based detectors by amplifying the BPVE and exploring the functional mechanism of chiral A-site design. Theoretical simulations and experiments reveal that the R-2MPAZE²⁺ with a large dipole moment and bulk stereo-configurations can induce an obvious structural reconfiguration to achieve a significant BPVE with an intrinsic radiation photovoltage (0.49 ± 0.09 V). Strikingly, chiral cations can optimize tolerance factor, increase ionic-migration energy, and modulate the band nature for realizing the strengthened carrier transport capacity and stability. The designed self-driven detectors delivered a considerable sensitivity of 65 µC Gy_air ^-1 cm^-2, a low detection limit of (67.3 nGy_air s^-1) and good detection stability. This research will enrich the material selection and component design of stable self-driven X-ray detectors, moving toward an environmentally friendly direction.