Detecting 100 fW cm⁻² Light with Trapped Electron Gated Organic Phototransistors

Abstract

Ultraweak light detection with solid-state and cooling-free photodetectors is important for both fundamental research and practical applications. A general phototransistor architecture for detecting ultraviolet-visible light down to 100 fW cm at room temperature is demonstrated. The exceptional sensitivity stems from an amplification process triggered by incident light. A responsivity of ≈10 A W is achieved.

Recent Progress on Localized Field Enhanced Two‐dimensional Material Photodetectors from Ultraviolet—Visible to Infrared

“…For these WS 2 photodetectors, an ultra‐low dark current of 10 −11 A and high responsivity of 1090 AW −1 are obtained under a low source/drain and a zero‐gate voltage at the wavelength of 520 nm. This result reveals the potential of floating‐gate devices for weak light detection . However, because the barrier is not high enough, the number of leakage electrons increases in durations of the illumination, leading to an unstable dark current.…”

Design strategies for two‐dimensional material photodetectors to enhance device performance

“…The floating‐gate structure shows infinite potential in ultra‐weak light detection. Recently, the floating‐gate based phototransistors have arisen prominent interest of researchers . By inducing weak photo‐generated carriers trapping in floating‐gate, the 2D materials channel current can be effectively modulated.…”

“…The ReS 2 (intrinsic n‐type) works as the channel and absorb layer, the excited electrons tunnel from channel into the MoS 2 layer resulting in a negative photoconductance after light irradiation as displayed in Figure D . Moreover, Zhang et al reported a organic floating‐gate phototransistors with ultra‐weak light detecting capacity under even 100 fW cm −2 power light . In 2015, Jang et al utilized a hybrid graphene/pentacene photogating phototransistor with floating‐gate structure .…”

“…Recently, the floating-gate based phototransistors have arisen prominent interest of researchers. [123][124][125] By inducing weak photo-generated carriers trapping in floating-gate, the 2D materials channel current can be effectively modulated. In 2016, Gong et al demonstrated the floating-gate phototransistors based on 2D WS 2 with Au nanoparticles embedded in gate layer as floating gate (as depicted in Figure 7A).…”

“…123 Moreover, Zhang et al reported a organic floating-gate phototransistors with ultra-weak light detecting capacity under even 100 fW cm −2 power light. 125 In 2015, Jang et al utilized a hybrid graphene/pentacene photogating phototransistor with floating-gate structure. 126 With the AuNPs acting as the floating-gate to trap electron under the grid voltage, the phototransistor can be exploited to work as not only a detector, but also as a photo-memory device.…”