Ga₂O₃-based solar-blind ultraviolet photodetectors are promising for low-background UV sensing but remain limited by the trade-off between sensitivity and effective transient photoresponse. Here, a Ga₂O₃/BaTiO₃ (BTO) heterojunction photodetector is developed to enable highly sensitive, self-powered detection of transient optical events through the synergistic coupling of photovoltaic and pyroelectric effects. Owing to the type-II band alignment and the spontaneous polarization of BTO, the device delivers an ultralow dark current on the order of 10^-13 A, a photo-to-dark current ratio exceeding 10⁶, and a specific detectivity of 2.63 × 10¹³ Jones. Under zero-bias and low-bias conditions, light-induced pyroelectric polarization modulation generates giant bipolar transient current pulses, contributing significantly to the self-powered photoresponse. Furthermore, the pyroelectric field also dynamically enhances interfacial carrier separation, thereby amplifying the overall photoresponse. This work offers a promising route toward intelligent solar-blind optoelectronic systems integrating event-driven sensing, self-powered operation, and hardware-level information security.

Two-dimensional (2D) crystals are attractive due to their intriguing structures and properties which are strongly dependent on the synthesis conditions. To achieve their superior properties, it is of critical importance to fully understand the growth processes and mechanisms for tailored design and controlled growth of 2D crystals. Due to the high spatiotemporal resolution and the capability to mimic the realistic growth conditions, in situ transmission electron microscopy (TEM) becomes an effective way to monitor the growth process in real-time at the atomic scale, which is expected to provide atomic-scale insights into the nucleation and growth of 2D crystals. Here we review the recent in situ TEM works on the formation of 2D crystals under electron irradiation, thermal excitation as well as voltage bias. The underlying mechanisms are also elucidated in detail, providing key insights into the nucleation and formation of 2D crystals.