Xinqin Liao

Recyclable and Green Triboelectric Nanogenerator

A recyclable and green triboelectronic nanogenerator (TENG) is developed based on triboelectrification and designed cascade reactions. Once triggered by water, the TENG can fully dissolve and degrade into environmentally benign end products. With features of rapid dissolution, reproductivity, and green electronic, the TENG has potential of serving as clearable energy harvester and nanosensor for health monitoring and motion sensing.

Ultrasensitive and stretchable resistive strain sensors designed for wearable electronics

Advanced wearable sensors for human motion detection are receiving growing attention and have great potential for future electronics. Herein, we demonstrate microcrack-assisted strain sensors using silver nanowires@patterned polydimethylsiloxane. Through designed percolating network microstructures, the strain sensors have significant inherent advantages, including simple fabrication processes and ultrahigh sensitivity far surpassing other stretchable sensing devices. Noteworthily, the strain sensors possess a tremendous gauge factor (GF) of 150 000 within a large stretchability of 60% strain range. The sensing mechanism depends on the change in electrical resistance, which is dramatically affected by a percolating-microcrack surface microstructure in the case of strain concentration of mechanical deformation. The superior sensing performance in conjunction with an appealing stretchability, reversibility, low creep and ultrahigh stability enables the strain sensors to act as wearable monitors and electronic skins for diverse applications, including but not limited to full-range detection of human body motions, as well as visual control of a light-emitting diode indicator, etc.

Flexible, Cuttable, and Self-Waterproof Bending Strain Sensors Using Microcracked Gold Nanofilms@Paper Substrate

Rapid advances in functional sensing electronics place tremendous demands on innovation toward creative uses of versatile advanced materials and effective designs of device structures. Here, we first report a feasible and effective fabrication strategy to integrate commercial abrasive papers with microcracked gold (Au) nanofilms to construct cuttable and self-waterproof crack-based resistive bending strain sensors. Via introducing surface microstructures, the sensitivities of the bending strain sensors are greatly enhanced by 27 times than that of the sensors without surface microstructures, putting forward an alternative suggestion for other flexible electronics to improve their performances. Besides, the bending strain sensors also endow rapid response and relaxation time of 20 ms and ultrahigh stability of >18 000 strain loading-unloading cycles in conjunction with flexibility and robustness. In addition, the concepts of cuttability and self-waterproofness (attain and even surpass IPX-7) of the bending strain sensors have been demonstrated. Because of the distinctive sensing properties, flexibility, cuttability, and self-waterproofness, the bending strain sensors are attractive and promising for wearable electronic devices and smart health monitoring system.

Enhanced Efficiency and Stability of Perovskite Solar Cells via Anti-Solvent Treatment in Two-Step Deposition Method

The low-cost inorganic-organic lead halide perovskite materials become particularly promising for solar cells with high photovoltaic conversion efficiency. The uniform and pinhole-free perovskite films play an important role for high-performance solar cells. We demonstrate an antisolvent treatment by controlling the PbI2 morphology to enhance the perovskite conversion and photophysical properties, including high absorption, crystallinity, and rapid carrier transfer. The fabricated perovskite solar cells show tremendous PCE improvement to about 16.1% from 12% with less hysteresis, and retain over 90% initial PCE after 30 days in ambient and dark atmosphere. In prospect, this antisolvent treatment will be a feasible route to prepare high-quality perovskite films including favorite photophysical properties.

Integrated active sensor system for real time vibration monitoring.

We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0–60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems.

Efficient Yttrium(III) Chloride-Treated TiO2 Electron Transfer Layers for Performance-Improved and Hysteresis-Less Perovskite Solar Cells

Hybrid organic-inorganic metal halide perovskite solar cells have attracted widespread attention, owing to their high performance, and have undergone rapid development. In perovskite solar cells, the charge transfer layer plays an important role for separating and transferring photogenerated carriers. In this work, an efficient YCl3 -treated TiO2 electron transfer layer (ETL) is used to fabricate perovskite solar cells with enhanced photovoltaic performance and less hysteresis. The YCl3 -treated TiO2 layers bring about an upward shift of the conduction band minimum (ECBM ), which results in a better energy level alignment for photogenerated electron transfer and extraction from the perovskite into the TiO2 layer. After optimization, perovskite solar cells based on the YCl3 -treated TiO2 layers achieve a maximum power conversion efficiency of about 19.99 % (19.29 % at forward scan) and a steady-state power output of about 19.6 %. Steady-state and time-resolved photoluminescence measurements and impedance spectroscopy are carried out to investigate the charge transfer and recombination dynamics between the perovskite and the TiO2 electron transfer layer interface. The improved perovskite/TiO2 ETL interface with YCl3 treatment is found to separate and extract photogenerated charge rapidly and suppress recombination effectively, which leads to the improved performance.

Ultra-thin, transparent and flexible tactile sensors based on graphene films with excellent anti-interference

Tactile sensing, which can reflect the displacement of touch, is considered to be an essential function for electronic skin to mimic natural skin. Here we report a novel tactile sensor with good sensitivity, excellent durability and fast response based on highly flexible and transparent conductor layers. The tactile device is simple in terms of structure consisting of a pair of compliant conductive plates, which were adhered to graphene films (GFs) on the surface layer of the polyethylene terephthalate (PET) substrate, and a transparent elastic adhesive sandwiched between the electrodes. The as-assembled tactile sensors can reflect one-dimensional (1D) touch tactile. And the resistance of the device is linearly related to the tactile of touch. Notably, the rate of resistance change is up to 420% when the displacement is changed by 25 mm. The tactile sensor features a high sensitivity of 0.143 mm−1, a long lifetime of 14 000 cyclic loading tests, and a fast response of 0.3 ms. Furthermore, the electrical signals of the tactile sensors are almost irrelevant to the interference signals such as vertical displacement, stress magnitude, stress acting area and bending strain. This rational design of innovative materials and devices presents great potential for electronic devices to completely replace the unique tough sensing properties of human skin.