Flexible Self‐Powered Photoelectrochemical Photodetector with Ultrahigh Detectivity, Ultraviolet/Visible Reject Ratio, Stability, and a Quasi‐Invisible Functionality Based on Lift‐Off Vertical (Al,Ga)N Nanowires

Abstract

electronics, flexible screens, automobile windshield navigation, and IoT (Internet of Things) applications, etc. [1][2] However, the working duration and energy consumption are the key problems that cannot be ignored for the wide applications of optoelectronic devices. Thanks to the ability for long-time working independently without energy consumption, self-powered photodetectors (PDs) can be the indispensable devices to make the detection systems economical and simple. [2,4,6] As the crucial components in the detection system, ultraviolet (UV) PDs are required for the wide applications in UV communication, fire warning, high-voltage corona detection, and ozone-hole monitoring. [1][2] Therefore, self-powered UV PDs with high flexibility and invisible functionality are pretty promising and necessary for the nextgeneration optoelectronic devices.Up to now, some research groups have developed the labor-less self-assembly approaches of fabricating the PDs and sensors requiring low power consumption. [7][8][9] For instance, Nasiri et al. reported a fully transparent ZnO PD with a gigantic photo-to-dark current ratio of 9.3 × 10 6 based on structural engineering. [7] With a self-assembly SnO 2 −graphene oxide nanoheterojunctions, Pargoletti et al. fabricated a room-temperature chemical sensor with an excellent UV light responsivity of 400 A W −1 . [9] Flexible self-powered ultraviolet (UV) photodetectors (PDs) with an invisible functionality are essential but challenging to be fabricated for the applications of next-generation optoelectronic devices. In this work, a flexible photo electrochemical (PEC) (Al,Ga)N PD with three excellent characteristics, which are the ultrahigh UV/visible reject ratio, ultrahigh detectivity, and transmissivity, is proposed and demonstrated successfully. By numerical simulations, it is also found that the cross-sectional absorption area should be a nonignorable factor affecting the photogenerated current under bending states. After continuous long-time working or preserving, the PD performance can keep quite stable. Thanks to the pretty thin bending section of GaN connecting layer, the piezoelectric charges generated by stress are proposed to have only a limited effect in the energy band and photocurrent density. Therefore, when bending or twisting the PD at a high degree for many times, both the stable on-off switching characteristics and photocurrent densities can still be achieved. With the demonstrated ultrahigh detectivity and stability of flexibility, this PD would enable a broad range of optoelectronic applications, including omnidirectional UV detection and wearable intelligent sensors.

Ultrathin In2O3 Nanosheets toward High Responsivity and Rejection Ratio Visible‐Blind UV Photodetection

“…The J ph approaches saturation at a higher bias voltage of 0.6 V, as shown in Figure S5b, Supporting Information, attributing to saturation photogeneration carriers transport at higher bias voltage. Therefore, we will focus on the performance of ultrathin In reported ultrathin nanomaterial-based aqueous-type PEC UV PDs [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] and are comparable with the record-high performance of recently reported PEC UV PDs, [17] as shown in Table S9, Supporting Information. The ultrahigh UV detection capability and the operation in weak alkaline electrolyte indicate that ultrathin In 2 O 3 NSs hold great prospects for underwater UV communication [12] (more detailed comparison in Table S6, Supporting Information).…”

“…The improved spectral selectivity is attributed to the wider bandgap of ultrathin In 2 O 3 NSs originating from the quantum confinement effect. [27] The spectral selectivity and R of ultrathin In 2 O 3 NSs PEC VBUV PDs outperform most reported aqueous-type PEC VBUV PDs, [26,[44][45][46][47][48] as shown in Figure 3c S8, Supporting Information, demonstrating their similar charge transport capability. The fitting R ct of ultrathin In 2 O 3 NSs is 5.797 Ω, which is 63% that of In 2 O 3 NPs, demonstrating a stronger interfacial charge transfer capability at the ultrathin In 2 O 3 NSs/electrolyte interface.…”

Flexible Monolithic Bifunctional Device Based on a Lift-off (In,Ga)N Film for Both Lighting and Self-Driven Detection

“…In our previous works, we proposed an electrochemical (EC) etching method to detach GaN-based materials. , In this work, we detach the (In,Ga)N film from the original Si substrate by the EC method and transfer it to a flexible, conductive substrate. The flexible conductive substrate was obtained by sputtering indium–tin oxide (ITO) on a polyethylene terephthalate (PET) substrate.…”

Flexible light-stimulated artificial synapse based on detached (In,Ga)N thin film for neuromorphic computing

“…By simulating biological neurons and synaptic functions, the artificial synaptic devices are the critical components for neuromorphic computing. In addition, flexible optoelectronic devices can be the indispensable parts of next-generation functional devices in the fields of flexible screens and wearable intelligent, etc [6][7][8][9]. Furthermore, flexible artificial synaptic devices with similar functions to the human brain can be widely used in various biomimetic fields, such as prosthetics, neurorobotics and health monitoring [4].…”