Advances in photoelectrochemical photodetectors empowered by novel micro-nano structures

Photoelectrochemical photodetectors (PEC PDs) play a pivotal role in modern optoelectronic technology, particularly self-powered PEC PDs capable of operating independently, which have become indispensable components of integrated optoelectronic systems. Among them, emerging PEC-type photodetectors have attracted significant research interest due to their outstanding self-powering capability, high photoresponse, simple fabrication processes, and low cost. Notably, due to PEC PDs possessing a unique semiconductor/electrolyte interface structure, their working mechanism not only includes the typical carrier generation, separation, and migration processes in traditional solid-state photodetectors, but also couples ion diffusion and electrochemical reactions, such as redox processes. Owing to this electrochemical mechanism and their operation within electrolyte solutions, PEC PDs can function efficiently and stably in liquid-phase environments without the need for external encapsulation, thereby offering distinct advantages for specialized applications in biological media, seawater, or other complex humid conditions. In recent years, low-dimensional nanomaterials, including zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) structures, have been widely utilized in the development of advanced, high-performance PEC PDs, demonstrating tremendous potential in PEC PD applications. Compared to conventional bulk semiconductor materials, these low-dimensional nanomaterials offer a larger specific surface area, a higher density of active sites, and superior charge modulation capabilities. These attributes significantly enhance light absorption, promote efficient photogenerated charge carrier separation, and improve overall photoresponse performance, making them ideal candidates for constructing advanced PEC PDs. Consequently, the rational design and integration of low-dimensional materials provide crucial support for enhancing device performance and expanding the functional capabilities of PEC PDs.Here, this review systematically summarizes recent advances in the application of low-dimensional semiconductor nanomaterials in PEC PDs. In this review, we focus on the structural design strategies and performance optimization approaches for various types of low-dimensional nanomaterials-including 0D nanostructures, 1D nanostructures, 2D nanostructures, and mixed-dimensional nanomaterials, highlighting their unique advantages in device structure design and performance optimization. In particular, performance-optimized techniques such as doping engineering, heterostructure construction, and surface functionalization are thoroughly discussed. Furthermore, we highlight the latest research progress on the integration of low-dimensional nanomaterials-based PEC PDs into advanced optoelectronic applications, including: (1) optoelectronic logic gates-focusing on introducing the application of multifunctional PEC PDs with bipolar light response in optoelectronic logic gates. (2) Optical communication-focusing on underwater communication based on PEC PDs and encrypted optical communication based on bipolar light response. (3) Optical imaging-introducing practical examples of single-pixel imaging systems and device array imaging based on PEC PD. (4) Biosensing-introducing the application of PEC PDs in the detection of biological substances such as glucose, nicotinamide adenine dinucleotide, ethanol, and phosphatidylcholine. Finally, this review provides an in-depth analysis of the key challenges currently facing PEC PDs, including issues such as electrolyte leakage/evaporation, limitations in large-scale device array integration, and the lack of comprehensive validation for imaging capabilities. And constructive perspectives on future research directions are also proposed. This work aims to offer theoretical insights and technical guidance for the development of high-performance, intelligent, and energy-efficient photoelectrochemical photodetection platforms, thereby accelerating the transition of PEC PDs from laboratory-scale investigations to real-world deployment.