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With the advent of the trillion sensor era, molybdenum disulfide (MoS2) offers intriguing future optical device opportunities due to qualities such as its novel optoelectronic properties and preferable form factors. However, while a fundamental understanding of device reliability under illumination is significantly important, most of the previous research has focused on persistent photocurrent (PPC) effects. For this reason, understanding of a clear mechanism remains elusive. Herein the work reported, electrical‐bias‐dependent device instability and net optical illumination effects of MoS2 thin‐film transistors (TFTs) are experimentally evaluated to decouple the origins of device instability coming from either net electrical bias stress or illumination stress. In addition, time‐dependent monitoring of relaxation behaviors under illumination at different wavelength hints that excess carrier generation and remnant electrons after annihilation during illumination play a key role in determination of photo‐initiated instability of a device. For practical suppression of device instability under ambient light, an operation scheme (using trapping time increase under positive bias) is adroitly utilized to provide reliable device performance. Systematic understanding of device instability of MoS2 TFTs, and of their suppression principles, is potentially beneficial for the design of next‐generation devices on the basis of 2D materials. [ABSTRACT FROM AUTHOR]

For robustness on security and ultralow power consumption for Internet of Things (IoT) sensors, including ultraminiaturization for high chip density, 2D multilayered ReS2 field‐effect transistors (FETs) combined with photoinsensitive single‐walled carbon nanotube (SWNT) FETs are demonstrated for application in light‐to‐frequency (LTF) conversion circuits. Herein, multilayered ReS2 FETs with a direct bandgap (≈1.5 eV) have discernible photoresponsivity of ≈17 A W−1 for red and ≈128 A W−1 for green, respectively, with photodetectivity (≈109 Jones), leading to excellent operation for photosensitive inverters, partly associated with the photoinsensitive SWNT FETs for p‐channel devices. Moreover, the electrical parameters for photosensitive complementary inverters, according to different wavelengths in the dark and under, red (λR = 660 nm), green (λG = 530 nm), and blue (λB = 450 nm) light, are experimentally extracted, and their SPICE simulation‐based validation on working principles of ring oscillators (ROs) is confirmed under light illumination. More impressively, ultralow power consumption for the proposed scheme is achieved due to both the direct bandgap and the large‐energy bandgap, as compared with conventional multilayered MoS2 FET‐based photosensitive inverters, rationally validating the promising opportunity for applications in the envisioned IoT sensor systems. [ABSTRACT FROM AUTHOR]

Photosensitive Complementary Inverters Based on n-Channel MoS2 and p-Channel MoTe2 Transistors for Light-to-Frequency Conversion Circuits To achieve better immunity on external noise in IoT sensors, light-to-frequency conversion (LFC) circuit is one of the essential elements. In article number 1900317, Sung Hun Jin and Seung Gi Seo demonstrate photosensitive complementary inverters and their ring oscillators, composed of multilayered n-channel molybdenum disulfide (MoS SB 2 sb ) and p-channel molybdenum ditelluride (MoTe SB 2 sb ) field-effect transistors (FETs). [Extracted from the article]