Achieving Record-High Photoelectrochemical Photoresponse Characteristics by Employing Co₃O₄ Nanoclusters as Hole Charging Layer for Underwater Optical Communication

Abstract

The physicochemical properties of a semiconductor surface, especially in low-dimensional nanostructures, determine the electrical and optical behavior of the devices. Thereby, the precise control of surface properties is a prerequisite for not only preserving the intrinsic material quality but also manipulating carrier transport behavior for promoting device characteristics. Here, we report a facile approach to suppress the photocorrosion effect while boosting the photoresponse performance of n-GaN nanowires in a constructed photoelectrochemical-type photodetector by employing Co3O4 nanoclusters as a hole charging layer. Essentially, the Co3O4 nanoclusters not only alleviate nanowires from corrosion by optimizing the oxygen evolution reaction kinetics at the nanowire/electrolyte interface but also facilitate an efficient photogenerated carrier separation, migration, and collection process, leading to a significant ease of photocurrent attenuation (improved by nearly 867% after Co3O4 decoration). Strikingly, a record-high responsivity of 217.2 mA W–1 with an ultrafast response/recovery time of 0.03/0.02 ms can also be achieved, demonstrating one of the best performances among the reported photoelectrochemical-type photodetectors, that ultimately allowed us to build an underwater optical communication system based on the proposed nanowire array for practical applications. This work provides a perspective for the rational design of stable nanostructures for various applications in photo- and biosensing or energy-harvesting nanosystems.

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

“…Most importantly, the intrinsic working principle coupled with additional surface modifications of the PEC photodetector enables low-cost, high-efficiency and versatile UOC applications by directly working in aqueous electrolyte environments. Previ-ously, we have explored different surface decoration strategies, including Pt, [10,11] MoS x , [16] Co 3 O 4 , [61] Rh/Cr 2 O 3 [12] and RuO x [62] to enhance the device performance of PEC photodetector or to achieve dual-polarity photoresponse behavior, [61][62][63][64] herein, we mainly explore the application of such PEC photodetector with simultaneous improvement of responsivity and response speed for possible UOC, [9,61] with a proof-of-concept demonstration.…”

High-Sensitivity Self-Powered Photodetector Fibers Using Hierarchical Heterojunction Photoelectrodes Enable Wearable Amphibious Optoelectronic Textiles

“…Flexible photodetectors capable of converting perceived light signals into electrical ones have attracted widespread attention in bionic eyes, electronic textiles, and optical communication systems. − Among them, fiber-shaped photodetectors (FPDs) are the ideal choice for portable electronics due to their lightweight, high flexibility, omnidirectional light absorption, and weaving capability. ,,− Recently, given the underwater health monitoring and ocean exploration, wearable underwater communication devices have become more critical for underwater workers . Underwater optical communication technology utilizes photons to convey information, offering superior transmission rates, energy efficiency, and minimal latency, effectively compensating underwater acoustic communication systems. , However, current solid-state FPDs rely on either electrons or holes as carriers and are unsuitable for aquatic environments due to their susceptibility to water. This leads to inadequate responsiveness, slow responses, deactivation of sensitive materials, and equipment malfunctions. ,, As such, there is an urgent need for innovative FPD architectures that can operate underwater while facilitating carrier transport, improving optical responsiveness and achieving faster response.…”

“…13 Underwater optical communication technology utilizes photons to convey information, offering superior transmission rates, energy efficiency, and minimal latency, effectively compensating underwater acoustic communication systems. 8,14 However, current solid-state FPDs rely on either electrons or holes as carriers and are unsuitable for aquatic environments due to their susceptibility to water. This leads to inadequate responsiveness, slow responses, deactivation of sensitive materials, and equipment malfunctions.…”

“…17,18 However, a large surface-volume ratio of nanowires makes them susceptible to corrosion or photocorrosion when exposed to air or liquid environments, resulting in poor performance. 8 Furthermore, the high density of surface states leads to nonradiative carrier recombination, worsening photoelectric efficiency. 8,17,19 Recently, researchers have attempted to construct a heterojunction to develop PEC devices suitable for underwater use.…”

“…8 Furthermore, the high density of surface states leads to nonradiative carrier recombination, worsening photoelectric efficiency. 8,17,19 Recently, researchers have attempted to construct a heterojunction to develop PEC devices suitable for underwater use. 7,20 However, present devices are composed of hard and flat substrates, resulting in a lack of flexibility, poor geometric compatibility with irregular surfaces, and difficulty in attachment to divers.…”