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The Si‐based self‐powered broadband photodiode (SSBP) is prized for its ability to swiftly detect light across a wide spectrum without requiring an external voltage. However, boosting its efficiency remains challenging due to its high refractive index and limited UV light penetration. A combination of Si with ZnGa2O4, an ultra‐wide‐bandgap spinel material, can bring new opportunities to address these shortcomings of SSBP. In this study, a ZnGa2O4/p‐Si heterojunction photodiode is presented, which is capable of detecting UV to near‐infrared light autonomously. Operating without bias, this device exhibits excellent rectification and detects wavelengths from 265 to 1000 nm, achieving impressive performance metrics such as a photo‐to‐dark current ratio of 5.8 × 104, response speed of less than 3 ms, responsivity of 117 mA W−1, and specific detectivity of 5.5 × 1012 Jones while the photodiode demonstrates exceptional stability and durability under harsh conditions. The versatility of this device is demonstrated by applying it to the optical imaging sensors and physically unclonable security devices. This study provides new inspirations for the development of the energy‐efficient and emerging optical sensing technologies. [ABSTRACT FROM AUTHOR]

Highlights: Blue micro-light-emitting diodes (μLED)-integrated gas sensors were fabricated as monolithic structure by directly loading sensing materials onto the μLED. SnO2 nanoparticles are activated by blue μLED and exhibit outstanding sensitivity to NO2 at μ-Watt power levels. Noble metal (Au, Pd, Pt)-decorated SnO2 showed the tunable gas selectivity for 4 target gases under blue light illumination. Micro-light-emitting diodes (μLEDs) have gained significant interest as an activation source for gas sensors owing to their advantages, including room temperature operation and low power consumption. However, despite these benefits, challenges still exist such as a limited range of detectable gases and slow response. In this study, we present a blue μLED-integrated light-activated gas sensor array based on SnO2 nanoparticles (NPs) that exhibit excellent sensitivity, tunable selectivity, and rapid detection with micro-watt level power consumption. The optimal power for μLED is observed at the highest gas response, supported by finite-difference time-domain simulation. Additionally, we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO2 NPs. The noble metals induce catalytic interaction with reducing gases, clearly distinguishing NH3, H2, and C2H5OH. Real-time gas monitoring based on a fully hardware-implemented light-activated sensing array was demonstrated, opening up new avenues for advancements in light-activated electronic nose technologies. [ABSTRACT FROM AUTHOR]

This work investigates the stability conditions for linear systems with time-varying delays via an augmented Lyapunov–Krasovskii functional (LKF). Two types of augmented LKFs with cross terms in integrals are suggested to improve the stability conditions for interval time-varying linear systems. In this work, the compositions of the LKFs are considered to enhance the feasible region of the stability criterion for linear systems. Mathematical tools such as Wirtinger-based integral inequality (WBII), zero equalities, reciprocally convex approach, and Finsler's lemma are utilized to solve the problem of stability criteria. Two sufficient conditions are derived to guarantee the asymptotic stability of the systems using linear matrix inequality (LMI). First, asymptotic stability criteria are induced by constructing the new augmented LKFs in Theorem 1. Then, simplified LKFs in Corollary 1 are proposed to show the effectiveness of Theorem 1. Second, asymmetric LKFs are shown to reduce the conservatism and the number of decision variables in Theorem 2. Finally, the advantages of the proposed criteria are verified by comparing maximum delay bounds in four examples. Four numerical examples show that the proposed Theorems 1 and 2 obtain less conservative results than existing outcomes. Particularly, Example 2 shows that the asymmetric LKF methods of Theorem 2 can provide larger delay bounds and fewer decision variables than Theorem 1 in some specific systems. [ABSTRACT FROM AUTHOR]

Nano-structural optical filters embedded in elastomers having high mechanical tunability provide the geometric degree of freedom for selective light manipulation. The active control of spectral information in typical structural optical filters is highly limited due to the substrate rigidity. Herein, we present mechanochromic transmissive optical filters by employing flexible and stretchable polymer-embedded silicon nanostructures. Si-based nanowire arrays (Si-NWAs) have been introduced to exhibit parametric resonance characteristics by controlling the period and/or diameter. Furthermore, the spectral shift phenomenon by increased diffraction efficiency was observed after the application of a uniaxial tensile force, which depends on the period of Si-NWAs with a large index contrast between the silicon nanowire and elastomer. The strain-sensitive properties of tunable Si-NWAs filters induced by light diffraction were calculated by simulation based on wave optics. The spectral tunability and light filtering features were simply demonstrated by stretching the Si-NWAs’ optical filters. Our proposed structure provides potential opportunities for a wide variety of applications, including dynamic color display, visual strain sensor and anti-counterfeiting.

Conventional radiative coolers (RCs) exhibit excellent cooling performance in horizontally-installed scenarios but are mainly limited to roofing materials due to their emitting direction. To increase the availability of RC application on the area of a building facade, this article proposes an oblique radiation-angled photonic structure (ORAPS). ORAPS can facilitate thermal emission toward the outer space, evade the adjacent building, and reflect incoming radiative heat in a direction perpendicular to the panel. Along with the theoretical basis of designing the structure, we present simulation-based cooling performance analyses for diverse environmental parameters. This demonstrates that an ORAPS is useful not only for densely packed megacities but also for thermoregulation during the winter season.