Breaking the Responsivity-Bandwidth Trade-Off Limit in GaN Photoelectrodes for High-Response and Fast-Speed Optical Communication Application

Underwater optical communication (UOC) has attracted considerable interest in the continuous expansion of human activities in marine/ocean environments. The water-durable and self-powered photoelectrodes that act as a battery-free light receiver in UOC are particularly crucial, as they may directly face complex underwater conditions. Emerging photoelectrochemical (PEC)-type photodetectors are appealing owing to their intrinsic aqueous operation characteristics with versatile tunability of photoresponses. Herein, a self-powered PEC photodetector employing n-type gallium nitride (GaN) nanowires as a photoelectrode, which is decorated with an iridium oxide (IrOx) layer to optimize charge transfer dynamics at the GaN/electrolyte interface, is reported. Strikingly, the constructed n-GaN/IrOx photoelectrode breaks the responsivity-bandwidth trade-off limit by simultaneously improving the response speed and responsivity, delivering an ultrafast response speed with response/recovery times of only 2 mu s/4 mu s while achieving a high responsivity of 110.1 mA W-1. Importantly, the device exhibits a large bandwidth with 3 dB cutoff frequency exceeding 100 kHz in UOC tests, which is one of the highest values among self-powered photodetectors employed in optical communication system.

Automated summary

Underwater optical communication (UOC) is gaining significant interest due to the continuous expansion of human activities in marine/ocean environments. Self-powered photoelectrodes that are water-durable and act as a battery-free light receiver in UOC play a crucial role in facing complex underwater conditions. A self-powered photoelectrochemical (PEC) photodetector using n-type gallium nitride (GaN) nanowires as a photoelectrode, decorated with an iridium oxide (IrOx) layer for optimizing charge transfer dynamics, breaks the responsivity-bandwidth trade-off limit and achieves an ultrafast response speed and high responsivity. This device also exhibits a large bandwidth, making it one of the highest performing self-powered photodetectors in optical communication systems.