Publications

Flexible electronic technology has attracted great attention due to its wide range of potential applications in the fields of healthcare, robotics, and artificial intelligence, etc. In this work, we have successfully fabricated flexible AlGaN/GaN high-electron-mobility transistors (HEMTs) arrays through a low-damage and wafer-scale substrate transfer technology from a rigid Si substrate. The flexible AlGaN/GaN HEMTs have excellent electrical performances with the Id,max achieving 290 mA/mm at Vgs = +2 V and the gm,max reaching to 40 mS/mm. The piezotronic effect provides a different freedom to optimize device performances, and flexible HEMTs can endure the larger mechanical distortions. Based on the piezotronic effect, we applied an external stress to significantly modulate the electrical performances of flexible HEMTs. The piezotronic effect modulated flexible AlGaN/GaN HEMTs exhibit great potential in human-machine interface, intelligent microinductor systems, and active sensors, etc, and introduce an opportunity to sensing or feedback external mechanical stimuli and so on.

Abstract Although natural evaporation absorbs substantial thermal energy from the ambient environment, efficiently utilizing this high‐entropy energy remains challenging. Here, the first water evaporation‐induced triboelectric nanogenerator is proposed. It only uses tap water to harvest low‐grade heat energy from the surroundings to convert it into electricity. The natural evaporation of the liquid can generate unintermittent electricity with an open‐circuit voltage of 382 V, a peak power of 0.42 mW, and three orders of magnitude enhancement up to 59.7 mJ mL −1 after consuming the same amount of tap water compared with the droplet‐based electricity generators. After which, the excellent power output lights 2 W LED and drives wearable electronic devices. This device also inhibits carbon steel materials' corrosion in solutions through the evaporation effect of the salt water on the spot. The present study provides novel insights for triboelectric nanogenerators regarding energy sources and promotes the practical application of evaporation‐power generation technology.

High-quality ultra-long alloyed CdS(x)Se(1)(-)(x) (0 < or = x < or = 1) whiskers were obtained by a simple thermal evaporation route. The near band-edge emission in these whiskers can be effectively guided at the sub-millimeter scale under continuous-wave laser excitation. As good optical waveguide cavities, the whiskers exhibit stimulated emissions under pulsed light excitation at room temperature for all compositions 0 < or = x < or = 1. The spectral positions of the sharp emission lines of the whiskers were tuned by their compositions, covering the spectral range from green to red.

Abstract The triboelectric nanogenerator (TENG) holds significant potential for applications in energy harvesting and environment monitoring. However, a notable challenge lies in developing a combined system capable of efficiently harvesting energy and providing real‐time self‐powered sensing. Here, a combined wind energy harvesting and speed sensing (EHSS) system is constructed based on a noncontact electricity‐induced constant‐voltage TENG (EICV‐TENG) that achieves constant output by coupling two different phases and incorporates a parasitic sensing module in a single phase. Through the optimization of system integration, the EICV‐TENG achieves a current density of 28.7 mA m −2 and an average power density of 0.26 W m −2 Hz −1 . With an optimal power management, the energy output efficiency of the EICV‐TENG reaches up to 96%. And EICV‐TENG can stably power 32 commercial hygrothermographs connected in parallel with the PMC at a wind speed of 7 m s −1 . In addition, the EHSS system demonstrates excellent real‐time sensing performance based on the correlation between the peak number of pulse output in a single phase and wind speeds. This work contributes to the advancement of TENG technology for a combined energy harvesting and self‐powered sensing system in the context of the Internet of Things (IoTs).

Abstract With the rapid development of transportation technology, people's lives are becoming more and more convenient, but the popularity of high speed transportation also increases the probability of emergencies. Therefore, it is necessary to conduct real‐time and accurate monitoring on transportation conditions to reduce the occurrence of emergencies. For possibly emergencies in other circumstances (e.g., meteorological disasters, geological disasters, and maritime disasters), emergency management is also critical to ensure the security of people and property. Prediction and early‐warning can help to detect abnormal situations and take measures, prior to potential risks. The basis of real‐time and effective transportation monitoring and emergency management requires a continuous and stable power supply for randomly distributed sensors and actuators. Triboelectric nanogenerators (TENGs) have been extensively investigated in different transportation circumstances to harvest the surrounding energy and drive distributed sensors for self‐powered wireless monitoring. This article surveys the research progress in TENGs in road transportation, bridge transportation, railway transportation, and maritime transportation, and related surrounding emergency management. Representative applications and the main achievements are summarized for these different application scenarios. A perspective on TENG research is given, and the remaining challenges facing TENGs in transportation and emergency management are discussed, along with potential solutions.

We report a fully enclosed cylindrical single-electrode-based triboelectric nanogenerator (S-TENG) consisting of a perfluoroalkoxy (PFA) ball with surface-etched nanowires, a floating latex balloon, and an Al electrode at the end of the balloon. The mechanism of the S-TENG includes two independent processes: contact-induced electrification between the PFA ball and the balloon and electrostatic induction between the charged PFA ball and the Al electrode. The relationships between the electrical outputs and the sliding distance of the PFA ball were systematically investigated by combining experimental results with finite-element calculations. The S-TENG delivers an output voltage up to 236 V and a short-circuit current of 4.8 μA, which can be used as a direct power source for driving tens of green light-emitting diodes (LEDs). The S-TENG is a potential power source for gas-flow harvesters, air navigation, and environmental monitoring.

Combining layered MoS2 flakes with conventional 3D semiconductors is a feasible route to fabricate high-quality heterojunction devices by harnessing the advantages of both materials. Here, we present a pressure-modulated heterojunction photodiode that is composed of an n-type multilayer MoS2 and a p-type GaN film via the piezo-phototronic effect. Under the illumination of 365 nm incident light, a strong photoresponse is observed with response and recovery times of ~66 and 74 ms, respectively. Under a pressure of 258 MPa, the photoresponsivity of this photodiode can be tuned by the piezo-phototronic effect arising from the GaN film to ~3.5 times. Because of the lowered junction barrier with an applied external pressure (strain), more photogenerated carriers can successfully pass through the junction area without recombination, which results in an enhancement effect. This work provides a possible path for the implementation of high-performance electronic and optoelectronic devices that are based on hybrid heterostructures via human interfacing. A device that combines the advantages of both conventional and modern atom-thick semiconductors has been created. Two-dimensional materials have a wide range of exotic electronic properties that could lead to new generation of electronic devices. However, achieving the broadest diversity of functionality will probably necessitate combing these flat materials with conventional semiconductors. Zhong Lin Wang from the Beijing Institute of Nanoenergy and Nanosystems and colleagues created a photodetector whose response can be tuned by applying pressure. They stacked two-dimensional molybdenum disulfide onto a thin film of gallium nitride to create a diode that generates an electrical signal on exposure to light with a wavelength of 365 nanometers. The team showed that the photoresponsivity could be boosted by a factor of 3.5 when an external pressure was applied. Here, we present a pressure-modulated heterojunction photodiode composed of n-type multilayer MoS2 and p-type GaN film by piezo-phototronic effect. Under the illumination of 365 nm incident light, strong photo-response is observed with a response time and recovery time of ~66 and 74 ms, respectively. Upon the pressure of 258 MPa, the photoresponsivity of this photodiode can be enhanced for about 3.5 times by piezo-phototronic effect arising from the GaN film. Due to the lowered junction barrier upon applying an external pressure (strain), more photo-generated carriers can successfully pass through the junction area without recombination, resulting in the enhancement effect.

Abstract The rapid development of aircraft in recent years has attracted more attention, especially the issue of safe flight for aircraft. Some existing angle detection sensors are difficult to adapt to the development speed of the current aircraft due to the expensive price and large size, so there is an immediate need for new technology that can suit the current aircraft. Here, a self‐powered digital angle sensor that is compact, simple, and lightweight is introduced. This sensor eliminates the need for an external power supply and demonstrates highly sensitive signal detection at the volt level when the variable structure of the aircraft is working. The sensor is designed with a thickness of 7.3 mm, a volume of 16.6 cm 3 , and a weight of 9.85 g. Its lightweight and compact structure allows for seamless integration into aircraft without causing significant impact. The sensor not only provides real‐time monitoring the aircraft's variable structure deflection states, including deflection direction and angle but also alerts operators to any anomalies in deflection. Its small size and self‐powered capability make it an ideal solution for aircraft applications, enhancing safety and efficiency during flight.

Abstract Due to their intrinsic flexibility, tunable conductivity, multiple stimulus‐response, and self‐healing ability, ionic conductive hydrogels have drawn significant attention in flexible/wearable electronics. However, challenges remain because traditional hydrogels inevitably faced the problems of losing flexibility and conductivity because of the inner water loss when exposed to the ambient environment. Besides, the water inside the hydrogel will freeze at the water icing temperatures, making the device hard and fragile. As a promising alternative, organogels have attracted wide attention because they can, to some extent, overcome the above drawbacks. Herein, a kind of organogel ionic conductor (MOIC) by a self‐polymerization reaction is involved, which is super stretchable, anti‐drying, and anti‐freezing. Meanwhile, it can still maintain high mechanical stability after alternately loading/unloading at the strain of 600% for 600 s (1800 cycles). Using this MOIC, high‐performance triboelectric nanogenerator (TENG) is constructed (MOIC‐TENG) to harvest small mechanical energy even the MOIC electrode underwent an extremely low temperature. In addition, multifunctional flexible/wearable sensors (strain sensor, piezoresistive sensor, and tactile sensor) are realized to monitor human motions in real time, and recognize different materials by triboelectric effect. This study demonstrates a promising candidate material for flexible/wearable electronics such as electronic skin, flexible sensors, and human‐machine interfaces.