Mn-doped Cu-based 2D hybrid perovskites with enhanced ferroelectric energy storage performance

In recent years, two-dimensional hybrid organic-inorganic perovskites (2D-HOIPs) have emerged as versatile platforms for multifunctional devices owing to their tunable optical and electronic properties. In this study, crystals of (C 6 H 5 C 2 H 4 NH 3 ) 2 Cu 1-x Mn x Cl 4 (abbreviated as PCMC, with x = 0, 0.02, 0.04, and 0.06) were grown from supersaturated solution at room temperature. Their structural, optical, ferroelectric, magnetic, and piezoelectric properties were examined by X-ray diffraction, UV-Vis spectroscopy, Raman spectroscopy, vibrating sample magnetometry (VSM), polarization-electric field (P-E) measurements, and piezoresponse force microscopy (PFM). XRD patterns confirm phase-pure single crystals with a strong (00n) preferred orientation. UV-Vis spectra reveal a transmission window of 500-650 nm and a systematic bandgap narrowing from 2.38 eV (x = 0) to 2.28 eV (x = 0.06). P-E loops demonstrate well-defined ferroelectric-like switching behavior, while M − H curves show composition-dependent magnetic responses, providing evidence for the coexistence of electric and magnetic order. Among all compositions, the S1 (x = 0.02) sample exhibits the most balanced performance, with a remanent polarization of 0.34 μC/cm 2 , a recoverable energy density of 0.42 mJ/cm 3 , and an energy-storage efficiency of 27.22%. PFM measurements further verify the piezoelectric character of the crystals and yield a maximum effective piezoresponse coefficient d 33 of approximately 451 p.m./V, accompanied by well-defined amplitude and phase hysteresis loops. These results highlight Mn-doped PCMC layered perovskites as promising candidates for next-generation energy-storage and electromechanical conversion devices.