Narrowband photodetector (NB‐PD) with selective light detection is critical for artificial vision and imaging. Intrinsic (optical‐filter‐free) NB‐PDs using conjugated organics or halide perovskite materials have been developed for eliminating the current complex filtering systems in NB‐PDs. However, the poor performance and external driving circuit of organic NB‐PDs as well as complex doping and uncontrollable recombination reactions in typical perovskite NB‐PDs have limited their applicational diversification. A p‐type self‐doped perovskite for intrinsic NB detection is reported which exhibits unique unbalanced electron–hole transfer kinetics. In conjunction with the optical field distribution, an unbalanced charge transport within the self‐doped perovskite triggers a wavelength‐dependent photo‐carrier collection, resulting in a novel spontaneous internal quantum efficiency narrowing mechanism. As a result, by reverting the device architectural polarity, an NB detection at a monochromic light of either red or UV is observed. Using such a revertible asymmetric device design, self‐powered NB‐PDs are successfully achieved. Briefly, the corresponding NB‐PDs exhibit excellent narrow response with a response window of ≈100 nm, high detectivity ≈1011 Jones, and fast response speed (f−3dB ≈ 60 kHz) at zero bias. These results demonstrate a new strategy of manipulating internal charge transport to realize power‐free and filter‐free intrinsic NB‐PDs.

A MME generator with a textured Fe–Ga alloy can generate over 1 mW power under a tiny magnetic field.

Internet of Things (IoT) is driving the development of new generation of sensors, communication components, and power sources. Ideally, IoT sensors and communication components are expected to be powered by sustainable energy source freely available in the environment. Here, we provide a breakthrough in this direction by demonstrating high output power energy harvesting from very low amplitude stray magnetic field, which exists everywhere, through magnetoelectric (ME) coupled magneto-mechano-electric (MME) energy conversion. ME coupled MME harvester comprised of multiple layers of amorphous magnetostrictive material, piezoelectric macro-fiber composite (MFC), and magnetic tip mass, interacts with external magnetic field to generate electrical energy. Comprehensive experimental investigation and theoretical model reveal that both magnetic torque generated through magnetic loading and amplification of magneto-mechanical vibration by ME coupling contribute towards the generation of high electrical power from the stray magnetic field around power cable of common home appliances. The generated electrical power from the harvester was sufficient for operating micro-sensors (gyro, temperature, and humidity sensing) and wireless data transmission system. These results will facilitate the deployment of IoT devices in emerging intelligent infrastructures.

The rapid enhancement of the thermoelectric (TE) figure‐of‐merit (zT) in the past decade has opened opportunities for developing and transitioning solid state waste heat recovery systems. Here, a segmented TE device architecture is demonstrated in conjunction with heterogeneous material integration that results in high unicouple‐level conversion efficiency of 12% under a temperature difference of 584 K. This breakthrough is the result of success in fabricating bismuth telluride/half‐Heusler segmented TE unicouple modules using a “hot‐to‐cold” fabrication technique that provides significantly reduced electrical and thermal contact resistance. Extensive analytical and finite element modeling is conducted to provide an understanding of the nature of thermal transport and contributions arising from various thermal and physical parameters. Bismuth telluride/half‐Heusler based segmented thermoelectric generators (TEGs) can provide higher practical temperature difference with optimum average zT across the whole operating range. These results will have immediate impact on the design and development of TEGs and in the general design of devices based upon heterostructures that take advantage of gradients in the figure of merit.

A magnetoelectric coupled magneto-mechano-electric energy conversion mechanism allows the generation of high electrical power from ambient stray magnetic fields around infrastructures.

The transition of autonomous vehicles into fleets requires an advanced control system design that relies on continuous feedback from the tires. Smart tires enable continuous monitoring of dynamic parameters by combining strain sensing with traditional tire functions. Here, we provide breakthrough in this direction by demonstrating tire-integrated system that combines direct mask-less 3D printed strain gauges, flexible piezoelectric energy harvester for powering the sensors and secure wireless data transfer electronics, and machine learning for predictive data analysis. Ink of graphene based material was designed to directly print strain sensor for measuring tire-road interactions under varying driving speeds, normal load, and tire pressure. A secure wireless data transfer hardware powered by a piezoelectric patch is implemented to demonstrate self-powered sensing and wireless communication capability. Combined, this study significantly advances the design and fabrication of cost-effective smart tires by demonstrating practical self-powered wireless strain sensing capability.

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Energy harvesting from extremely low frequency magnetic fields using magneto‐mechano‐electric (MME) harvesters enables wireless power transfer for operating Internet of Things (IoT) devices. The MME harvesters are designed to resonate at a fixed frequency by absorbing AC magnetic fields through a composite cantilever comprising of piezoelectric and magnetostrictive materials, and a permanent magnetic tip mass. However, this harvester architecture limits power generation because volume of the magnetic end mass is closely coupled with the resonance frequency of the device structure. Here, a method is demonstrated for maintaining the resonance frequency of the MME harvesters under all operating conditions (e.g., 60 Hz, standard frequency of electricity in many countries) while simultaneously enhancing the output power generation. By distributing the magnetic mass over the beam, the output power of the harvester is significantly enhanced at a constant resonance frequency. The MME harvester with distributed forcing shows 280% improvement in the power generation compared with a traditional architecture. The generated power is shown to be sufficient to power eight different onboard sensors with wireless data transmission integrated on a drone. These results demonstrate the promise of MME energy harvesters for powering wireless communication and IoT sensors.