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Defect-engineered black tetragonal-tungsten-bronze ferroelectric crystal for full spectrum absorption and broadband photoelectronic conversion

Year: 2025

Type: article

Abstract: Ferroelectric crystals have emerged as promising candidates for exotic optoelectronic platforms. However, the wide bandgaps of transparent ferroelectric crystals restrict their ultraviolet optical activity, hindering broadband photoelectric conversion. Herein, a hierarchical defect engineering strategy is proposed for ferroelectric oxides to achieve full-spectrum optical absorption and boost broadband self-powered photodetection. Based on the transparent calcium barium niobate crystal, red Ce:CSBN is designed through the cooperative isovalent substitution of Sr2+ and aliovalent substitution of Ce3+. Furthermore, a black Ce:CSBN crystal is fabricated via thermal reduction, which demonstrated ultra-broadband absorption from the ultraviolet to the mid-infrared range. This extended absorption capability is attributed to the judiciously modulated oxygen vacancies. Consequently, self-powered photodetection is realized in the 250–5000 nm range with a high responsivity of >1 mA/W, representing the widest responsive range among all-known ferroelectric detectors. More impressively, a reversible red-black transition is achieved by controlling oxygen vacancy concentration. The authors propose a hierarchical defect engineering strategy for ferroelectric oxides to achieve full-spectrum optical absorption and boost broadband self-powered photodetection, realizing self-powered photodetection in the 250–5000 nm range with a responsivity of >1 mA/W.

Source: Nature Communications

DOI: 10.1038/s41467-025-64507-7