Regulating the Stereoisomerism of Diammonium Cations to Construct Polar Dion-Jacobson Hybrid Perovskites for Self-Powered X-ray Detection

Dion-Jacobson (DJ) hybrid perovskite (HP) single-crystal photodetectors often require operation under external bias due to the centrosymmetric structure of the material, which is not conducive to the intelligence and lightweight of the devices. To solve this problem, the key issue is how to regulate the noncovalent interaction between interlayer diammonium cations and inorganic frameworks to successfully induce polarity. However, there is a lack of research on the relationship between the configuration of diammonium cations and the structure symmetry of DJ HPs. Herein, we successfully constructed a series of polar DJ HPs (1,3-BMACH)PbX4 (X = Cl, Br, I; 1,3-BMACH is 1,3-bis(aminomethyl)cyclohexane) by changing the configuration of organic cations. It was found that the hydrogen bonding strength between 1,3-BMACH2+ cations and the bilateral inorganic framework is different, and it causes the inorganic layer to be more twisted, resulting in a deviation of the positive and negative charge centers in (1,3-BMACH)PbX4 (X = Cl, Br, I) and successfully inducing polarity. Subsequently, we achieved efficient self-powered X-ray detection in the single-crystal device of (1,3-BMACH)PbBr4 through polarity-induced bulk photovoltaic effect, which owns outstanding sensitivity (157.3 μC Gy–1 cm–2, 0 V bias) and stability under X-ray radiation. Studying the relationship between the configuration of diammonium cations and the crystal structure in DJ HPs can help us design more efficient self-powered optoelectronic devices.