Synergistic Effect of Chirality and Symmetry Reduction Enables Metal‐Free Perovskite Single Crystal With Stable Self‐Driven X‐ray Detection

ABSTRACT 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‐NH 4 I 3 ·H 2 O SCs with right‐ or left‐handed screw conformations through incorporating chiral cations of R/S‐2MPAZE 2+ 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‐2MPAZE 2+ 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.