Piezophototronic Devices

Multifunctional micro/nano devices and systems are of important applications in smart electronics for health care,human-machine interfacing,infrastructure monitoring and security.In recent years,piezophototronic effect is developed fast since it offers a new method to improve/tune the optoelectronic

A columnar multi-layer sliding triboelectric nanogenerator for water wave energy harvesting independent of wave height and direction

The ocean,with its highly variable and complex meteorological conditions,harbors enormous renewable resources.Triboelectric nanogenerators(TENGs),which possess unique advantages,show exciting prospects in water wave energy collection.How to design and optimize TENGs to cover all characteristic water wave energies and achieve efficient energy utilization is emergent.In this paper,we carefully designed and fabricated a columnar multi-layer sliding TENG(CMLS-TENG)that can harvest water wave energy independent of wave height and direction.Drive rods with a hollow acrylic spherical shell were introduced to deliver wave energy,ensuring that the CMLS-TENG can work in all directions from 0°to 360°.Based on the sliding structure,switching the optimized CMLS-TENG is independent of wave heights.The optimized CMLS-TENG can achieve a total power density of 730 mW/m^(3) at a wave height of only 4.8 cm regardless of wave direction,which can illuminate multiple light-emitting diodes(LEDs)to provide lighting and provide power to a watch and a hygrometer for temperature and humidity monitoring.This work provides new choices and hopes for the effective collection of full-range water wave energy.

Manipulating functional groups between polyvinylidene difluoride and nanoparticles for high-performance triboelectric nanogenerator

Interface functional groups play an essential role in regulating the electrical properties of bulk materials.In this work,we designed a novel strategy to explore a new way to enhance triboelectric performance by regulating the functional groups between nano-fillers and polymer matrix without obvious changes in the dielectric constant.The silica nanoparticles(SNPs)modified perfluoro-silane coupling agents(PFSCAs)with different chain lengths were added to the polyvinylidene difluoride to regulate the transferred charge density(TCD)of triboelectric nanogenerators(TENGs).When the doping concentration of perfluorodecyl modified SNPs is 2.25 wt.%,the nanocomposite film based TENG exhibits the maximum TCD of 166μC/m^(2)and power density of 3.12 W/m^(2)which are 6 times and 39 times as big as those of pure polyvinylidene difluoride(PVDF)film.The charge accumulation and decay process show that interface functional groups dominate the performance of TENGs.Then,a Fermi level model is proposed and why the TCD could be regulated by the concentration of nanoparticles in bulk materials is explained.This work provides a new concept for understanding the performance of TENG independent dielectric constant and points out a new direction for enhancing TENG’s performance,since wealthy functional groups with selectivity are applicable.

Fabrication of highly luminescent TiO_(2):Eu^(3+) thin film with low annealing temperature requirement by co-doping with Sn^(4+) ions

Rare earth(RE)-doped TiO_(2)thin films possess important applications in modern optoelectronic devices.However,the high annealing temperature requirement remains a critical restriction in device fabrications.In this work,TiO_(2)thin films doped with trivalent europium(Eu^(3+))ions were fabricated by a convenient sol-gel approach and subsequent annealing treatment.Interestingly,it is found that the optimal post-annealing temperature of TiO_(2):Eu^(3+)thin film is dramatically reduced from 800 to 300℃by incorporating 10 at%Sn^(4+)into the sol precursor.The Sn-incorporated film annealed at 300℃shows a 4-fold enhancement in photoluminescence(PL)intensity related to Eu^(3+)ions to the optimized Sn-free film.Systematic analysis reveals that this enhancement is attributed to Sn element promoting the crystallization of both anatase TiO_(2)and rutile SnO_(2)clusters at 300℃,which provides sufficient SnO_(2)/TiO_(2)crystal boundary facilitating Eu^(3+)to occupy and sensitized by SnO_(2)crystals.These results provide valuable insights into fabricating highly luminescent RE-doped TiO_(2)thin films with low annealing temperature requirement,which is essential for designing optoelectronic devices based on RE materials more freely in the future.

基于第三代半导体的压电电子学和压电光电子学器件

当一个均匀的应变施加到非中心对称的半导体单晶上时,半导体内部将产生压电势,其表面将产生静态的压电极化电荷,这种现象普遍存在于第三代半导体(如ZnO,GaN,CdS)中.应变引起的这种压电势或压电极化电荷可以静态和/或动态地调控界面电荷的输运和光电过程.通过将压电、光激发和半导体特性进行耦合,诞生了两个全新的研究领域,即压电电子学和压电光电子学.十几年来,这两个领域得到了广泛的关注,并在基础科学和器件应用方面取得了巨大的研究进展.本文对近年来这两个领域在器件应用方面的实验进展情况做了简要综述,并对这两个学科的未来发展进行了展望.

Self-powered electrochromic devices with tunable infrared intensity

Triboelectric nanogenerator(TENG) is an efficient way to convert ambient mechanical energy into electricity to power up portable electronics.In this work,a flexible infrared electrochromical device(IR-ECD)with stable performances was assembled with a TENG for building self-powered infrared detector with tunable intensity.As driven by TENG,the electrochromic device could be operated in the mid-IR region due to the reversible electrochromic reactions.An average infrared reflectance contrast of 46% was achieved in 8–14 lm regions and as well a clear thermal image change can be observed.This work indicates that the TENG-driven infrared electrochromical device has potential for use in self-powered camouflage and thermal control.

Enhanced NO_2 gas sensing of a single-layer MoS_2 by photogating and piezo-phototronic effects

NO_2 sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However,traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here, we report a simply and reliable flexible NO_2 sensor based on single-layer MoS_2. The flexible sensor exhibits high sensitivity to NO_2 gas due to ultra-large specific surface area and the nature of two-dimensional(2 D) semiconductor. When the NO_2 is 400 ppb(parts per billion), compared with the dark and strain-free conditions, the sensitivity of the single-layer sensor is enhanced to 671% with a625 nm red light-emitting diode(LED) illumination of 4 mW/cm^2 power under 0.67% tensile strain.More important, the response time is dramatically reduced to $16 s and it only needs $65 s to complete90% recovery. A theoretical model is proposed to discuss the microscopic mechanisms. We find that the remarkable sensing characteristics are the result of coupling among piezoelectricity, photoelectricity and adsorption-desorption induced charges transfer in the single-layer MoS_2 Schottky junction based device.Our work opens up the way to further enhancements in the sensitivity of gas sensor based on single-layer MoS_2 by introducing photogating and piezo-phototronic effects in mesoscopic systems.

Recent Progress of Functional Fiber and Textile Triboelectric Nanogenerators:Towards Electricity Power Generation and Intelligent Sensing

Rapid development in wearable electronics has brought huge convenience to human life and gradually penetrated into various indispensable felds,such as health monitoring,medical assistance,smart sports,object tracking and smart home,etc.However,the suitable energy supply system for these wearable electronics remains an important issue to address.Fiber and textile triboelectric nanogenerators(f/t-TENGs),capable of converting biomechanical energy into electricity,have promising features to act as a mobile sustainable power source for wearable electronics or directly serve as an intelligent self-powered sensing solution.Compared with the low-output piezoelectric nanogenerators,hard-to-wear electromagnetic generators and other bulk TENGs,the fber/textile TENG may be the best type of wearable human mechanical energy harvester at present.Herein,this review comprehensively introduces the recent progress of smart fbers and textiles with a highlight on triboelectric nanogenerators,including the general materials and structures of fber/textile shaped electronics,various fber and textile devices for triboelectric/triboelectric-integrated energy harvesting and self-powered smart sensing systems.Moreover,the advance of f/t-TENGs with multifunctionality and large-scale textile processing techniques is summarized as well.Finally,the challenges and perspectives of f/t-TENGs for future improvement,large-scale production and emerging applications are thoroughly discussed as well.

Controllable design of high-efficiency triboelectric materials by functionalized metal–organic frameworks with a large electronwithdrawing functional group

Triboelectric nanogenerator(TENG)can directly convert mechanical energy into electric energy.However,the triboelectric materials are limited to the triboelectric series.Here,for the first time,we choose the isostructural UiO-66-X(X=H,NH_(2),NO_(2),and Br)family as triboelectric materials to investigate the underlying relationships between different functional groups and the triboelectric performance of TENG.Unlike traditional triboelectric material organic polymers,metal–organic frameworks(MOFs)can be oriented design synthesis and functionalized with various functional groups.The results demonstrate that the largest output voltage and current are from UiO-66-NO_(2) TENG,and are about 23.79 V and 0.29μA,which are 3.19 and 4.14 times over that of the UiO-66 TENG,respectively.The working mechanism of the MOF TENG was discussed in depth through experiments and theoretical calculations.This work proves a novel strategy to obtain high output properties by functionalized MOFs with large electron-withdrawing functional groups and promising guidance for the choice of high-efficiency triboelectric materials.

Piezoelectric and deformation potential effects of straindependent luminescence in semiconductor quantum well structures

The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We analytically solved an infinite quantum well （IQW） model with strain, in the framework of the 6 × 6 k.p Hamiltonian for the valence states, to directly assess the interplay between the spin-orbit coupling and the strain-induced deformation potential for the interband momentum-matrix element. We numerically addressed problems of both the infinite and IQWs with piezoelectric fields to elucidate the effects of the piezoelectric potential and the deformation potential on the straindependent luminescence. The experimentally measured photoluminescence variation as a function of pressure can be qualitatively explained by the theoretical results.