Electrochemical half-reaction-assisted sub-bandgap photon sensing in a graphene hybrid phsotodetector

Abstract

The photogating effect has been previously utilized to realize ultra-high photoresponsivity in a semiconductor-graphene hybrid photodetector. However, the spectral response of the graphene hybrid photodetector was limited by the bandgap of the incorporated semiconductor, which partially compromised the broadband absorption of graphene. Here, we show that this limitation can be overcome in principle by harnessing the electron-accepting ability of the electrochemical half-reaction. In our new graphene phototransistor, the electrochemical half-reaction serves as an effective reversible electron reservoir to accept the photoexcited hot electron from graphene, which promotes the sub-bandgap photosensitivity in a silver chloride (AgCl)-graphene photodetector. The photoconductive gain of~3 × 10 9 electrons per photon in the AgCl-graphene hybrid is favored by the long lifetime of photoexcited carriers in the chemically reversible redox couple of AgCl/Ag 0 , enabling a significant visible light (400-600 nm) responsivity that is far beyond the band-edge absorption of AgCl. This work not only presents a new strategy to achieve an electrically tunable sub-bandgap photoresponse in semiconductor-graphene heterostructures but also provides opportunities for utilizing the electrochemical half reaction in other two-dimensional systems and optoelectronic devices.

Immobilization of Growth Factors for Cell Therapy Manufacturing

“…Nanoparticles have recently gained prominence as advanced drug delivery systems in the biotechnology and pharmaceutical industries. In the context of GF immobilization, nanoparticles can be loaded with GFs, facilitating controlled delivery (Wang et al, 2017). For instance, VEGF was loaded into dermatan sulfate sodium salt-poly-l-lysine (DS-PLL) and gum tragacanthpoly-l-lysine (GT-PLL) nanoparticles with loading efficiencies of 93.1 and 80.2%, respectively (Zandi et al, 2020).…”

“…The properties of materials and solutions used to immobilize the GF can be tuned to control adsorption (King and Krebsbach, 2012). Some of the disadvantages of this approach are low loading efficiency, poor control over release, and minimum spatial control (Midy et al, 1998;Budiraharjo et al, 2013;Wang et al, 2017). This approach has been utilized to immobilize different types of GFs, including BMP-2, FGF, and FGF-2 (Ziegler et al, 2008;Budiraharjo et al, 2013).…”

“…LbL is based in the incorporation of several layers of matrix with GF adsorbed on it. This immobilization strategy depends mainly on electrostatic interactions between GFs and oppositely charged electrolytes, although, hydrophobic interactions and hydrogen bonds are also present (Zhang et al, 2015;Wang et al, 2017). In addition to improving release control and spatial distribution, LbL is a simple and inexpensive technique.…”

“…To date, the majority of the literature has focused on the production of immobilized GF (iGF) for tissue engineering applications (Lee et al, 2011;Cabanas-Danés et al, 2014;Reed and Wu, 2014;Hajimiri et al, 2015;Wang et al, 2017;Atienza-Roca et al, 2018). Therefore, this review aims to discuss general approaches to immobilize GFs in the context of cell therapy manufacturing.…”

Strategies for Air‐Stable and Tunable Monolayer MoS2‐Based Hybrid Photodetectors with High Performance by Regulating the Fully Inorganic Trihalide Perovskite Nanocrystals

“…In contrast, owing to the efficient separation of the charge carriers at the interface, the response rates of the HPs are accelerated, and a τ rise value of 92 ms can be realized, but τ rise and τ decay of the HPs are extended to some extent with the rising concentration. Many reports have shown that the generation process of the high photocurrent helps to prolong the carrier lifetime, τ lifetime . On the other hand, the high carrier mobility in the high‐quality channel contributes to a shorter carrier transit time, τ transit .…”