Ultrasensitive Self-Powered Flexible Crystalline β-Ga₂O₃-Based Photodetector Obtained through Lattice Symmetry and Band Alignment Engineering

Due to its portable and self-powered characteristics, the construction of Ga 2 O 3 -based semiconductor flexible devices that can improve the adaptability in various complex environments have drawn great attention in recent decades. However, conventional Ga 2 O 3 -based flexible heterojunctions are based on either amorphous or poor crystalline Ga 2 O 3 materials, which severely limit the performance of the corresponding devices. Here, through lattice-symmetry and energy-band alignment engineering, we construct a high-quality crystalline flexible NiO/β-Ga 2 O 3 p – n self-powered photodetector. Owing to its suitable energy-band alignment structure, the device shows a high photo-to-dark current ratio (1.71 × 10 5 ) and a large detection sensitivity (6.36 × 10 14 Jones) under zero bias, which is superior than most Ga 2 O 3 self-powered photodetectors even for those based on rigid substrates. Moreover, the fabricated photodetectors further show excellent mechanical stability and robustness in bending conditions, demonstrating their potential practical applications in flexible optoelectronic devices. These findings provide insights into the manipulation of crystal lattice and energy band engineering in flexible self-powered photodetectors and also offer guideline for designing other Ga 2 O 3 -based flexible electronic devices.