Regulating 3D Phase in Quasi-2D Perovskite Films for High-Performance and Stable Photodetectors.

The charge transport in quasi-2D perovskites limits their applications despite the superior stability and optoelectronic properties. Herein, a novel strategy is proposed to enhance the charge transport by regulating 3D perovskite phase in quasi-2D perovskite films. The carbohydrazide (CBH) as an additive is introduced into (PEA) MA Pb I precursors, which slows down the crystallization process and improves the phase ratio and crystal quality of the 3D phase.

Effects of Chemical Valences of Sulfur on the Performance of CsFAMA Perovskite Solar Cells.

The low electrical conductivity and the high surface defect density of the TiO electron transport layer (ETL) limit the quality of the following perovskite (PVK) layers and the power conversion efficiency (PCE) of corresponding perovskite solar cells (PSCs). Sulfur was reported as an effective element to passivate the TiO layer and improve the PCE of PSCs. In this work, we further investigate the effect of chemical valences of sulfur on the performance of TiO/PVK interfaces, CsFAMA PVK layers, and solar cells using TiO ETL layers treated with NaS, NaSO, and NaSO, respectively.

Bridging Effects of Sulfur Anions at Titanium Oxide and Perovskite Interfaces on Interfacial Defect Passivation and Performance Enhancement of Perovskite Solar Cells.

Interfacial defects at the electron transport layer (ETL) and perovskite (PVK) interface are critical to the power conversion efficiency (PCE) and stabilities of the perovskite solar cells (PSCs) via significantly affecting the quality of both interface contacts and PVK layers. Here, we demonstrate a simple ionic bond passivation method, employing NaS solution treatment of the surface of titanium dioxide (TiO) layers, to effectively passivate the traps at the TiO/Cs(MAFA)Pb(BrI) PVK interface and enhance the performance of PSCs. X-ray photoelectron spectroscopy and other characterizations show that the NaS treatment introduced S ions at the TiO/PVK interface, where S ions effectively bridged the TiO ETL and the PVK layer via forming chemical bonds with Ti atoms and with uncoordinated Pb atoms and resulted in the reduced defect density and improved the crystallinity of PVK layers.

Highly efficient copper halide scintillators for high-performance and dynamic X-ray imaging.

Progress towards high performance X-ray detection and dynamic imaging applications, including nondestructive inspection, homeland security, and medical diagnostics, requires scintillators with a high light yield, a reasonable decay time, low cost, and eco-friendliness. Recently, copper halide scintillators have drawn tremendous attention due to their outstanding radioluminescence performance. Here, we first employed β-CsCuCl as a high-performance scintillator, with a photoluminescence quantum yield (PLQY) of 94.

High-sensitivity fiber-optic X-ray detectors employing gadolinium oxysulfide composites.

Radiation detection technologies have been applied in broad fields such as security inspection, medical diagnosis, environment monitoring and scientific analysis. Fiber-optic radiation detectors exhibit unique advantages including miniaturization, resistance to water, remote monitoring, and distributable detection. However, the low sensitivity and the high limit-of-detection limit its practical applications.

Effects of ITO Substrate Hydrophobicity on Crystallization and Properties of MAPbBr Single-Crystal Thin Films.

Fabricating perovskite single-crystal thin films (SCTFs) in controllable manner is the major challenge for the promising potential applications in optoelectronic devices. Although modifying the substrate surface is frequently used to realize the controlled growth of perovskite SCTFs, it is still unclear how the substrate condition affects the crystallization process. In this work, we systemically investigated the effects of the surface hydrophobicity of indium tin oxide substrates on the crystallization process of MAPbBr SCTFs prepared by the space-confined method.

Perovskite-Betavoltaic Cells: A Novel Application of Organic-Inorganic Hybrid Halide Perovskites.

Betavoltaic devices are very appealing to applications in out-space exploration, deep-sea facilities, and implantable medical devices for their ultralong lifetime and high power density. The key to further improve the betavoltaic device efficiency is to find proper semiconductor materials with long carrier diffusion lengths and having strong interactions with β-particles. Halide perovskite would be a promising candidate material for betavoltaics due to the long carrier diffusion length, the high defect tolerance, the strong interaction with β-particles, and the wide adjustable band gap.

Tailoring the energy band in flexible photodetector based on transferred ITO/Si heterojunction via interface engineering.

Interface engineering is an important method to modulate electronic structures for improving the physical properties of semiconductors as well as designing novel devices. Recently, development of flexible electronic devices based on inorganic thin films on flexible substrates, which provides solutions to meet the emerging technological demands, may also expend the methodology of interface engineering. Herein, a semitransparent photodetector based on an indium-tin oxide (ITO)-on-silicon (Si) heterojunction was fabricated on a flexible substrate and investigated under mechanical bending strains.

Thermal Release Transfer Printing for Stretchable Conformal Bioelectronics.

Soft neural electrode arrays that are mechanically matched between neural tissues and electrodes offer valuable opportunities for the development of disease diagnose and brain computer interface systems. Here, a thermal release transfer printing method for fabrication of stretchable bioelectronics, such as soft neural electrode arrays, is presented. Due to the large, switchable and irreversible change in adhesion strength of thermal release tape, a low-cost, easy-to-operate, and temperature-controlled transfer printing process can be achieved.

Ultrafast response flexible breath sensor based on vanadium dioxide.

Real-time monitoring of breath can provide clinically relevant information about apnea syndrome and other important aspects of human physiology. Here, we introduce a flexible skin-like breath sensor developed by transfer-printing vanadium dioxide (VO) thin films on PDMS substrates. This flexible breath sensor can conformably laminate on the skin under the nose with different curvatures and operate at different environment temperatures through day and night.

A Ferroelectric Ceramic/Polymer Composite-Based Capacitive Electrode Array for In Vivo Recordings.

A new implantable capacitive electrode array for electrocorticography signal recording is developed with ferroelectric ceramic/polymer composite. This ultrathin and electrically safe capacitive electrode array is capable of attaching to the biological tissue conformably. The barium titanate/polyimide (BaTiO /PI) nanocomposite with high dielectric constant is successfully synthesized and employed as the ultrathin dielectric layer of the capacitive BaTiO /PI electrode array.

Highly stretchable and shape-controllable three-dimensional antenna fabricated by "Cut-Transfer-Release" method.

Recent progresses on the Kirigami-inspired method provide a new idea to assemble three-dimensional (3D) functional structures with conventional materials by releasing the prestrained elastomeric substrates. In this paper, highly stretchable serpentine-like antenna is fabricated by a simple and quick "Cut-Transfer-Release" method for assembling stretchable 3D functional structures on an elastomeric substrate with a controlled shape. The mechanical reliability of the serpentine-like 3D stretchable antenna is evaluated by the finite element method and experiments.

Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes.

Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm(-2) even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state.