Organolead halide perovskites have emerged as the most promising materials for various optoelectronic devices, especially solar cells, because of their excellent optoelectronic properties. Here, we present the first report of low-voltage high-gain phototransistors based on perovskite/organic-semiconductor vertical heterojunctions, which show ultrahigh responsivities of ~10⁹A W^–1 and specific detectivities of ~10¹⁴ Jones in a broadband region from the ultraviolet to the near infrared. The high sensitivity of the devices is attributed to a pronounced photogating effect that is mainly due to the long carrier lifetimes and strong light absorption in the perovskite material. In addition, flexible perovskite photodetectors have been successfully prepared via a solution process and show high sensitivity as well as excellent flexibility and bending durability. The high performance and facile solution-based fabrication of the perovskite/organic-semiconductor phototransistors indicate their promise for potential application for ultrasensitive broadband photodetection.

The deformation of nanocomposites containing graphene flakes with different numbers of layers has been investigated with the use of Raman spectroscopy. It has been found that there is a shift of the 2D band to lower wavenumber and that the rate of band shift per unit strain tends to decrease as the number of graphene layers increases. It has been demonstrated that band broadening takes place during tensile deformation for mono- and bilayer graphene but that band narrowing occurs when the number of graphene layers is more than two. It is also found that the characteristic asymmetric shape of the 2D Raman band for the graphene with three or more layers changes to a symmetrical shape above about 0.4% strain and that it reverts to an asymmetric shape on unloading. This change in Raman band shape and width has been interpreted as being due to a reversible loss of Bernal stacking in the few-layer graphene during deformation. It has been shown that the elastic strain energy released from the unloading of the inner graphene layers in the few-layer material (∼0.2 meV/atom) is similar to the accepted value of the stacking fault energies of graphite and few layer graphene. It is further shown that this loss of Bernal stacking can be accommodated by the formation of arrays of partial dislocations and stacking faults on the basal plane. The effect of the reversible loss of Bernal stacking upon the electronic structure of few-layer graphene and the possibility of using it to modify the electronic structure of few-layer graphene are discussed.

Wearable electronic knitwear has recently been gaining the attention of both researchers and industrial sectors. Combining knitting technology with electronics may become a dominant trend in the future. There is a need to develop an analytical equation to model the complex resistive network for a given set of conductive stitches in order to meet the high demand for rapid prototype designing of smart knitwear. Currently, a matrix equation with high dimensionality must be solved, which is impractical and requires high computational power, retarding the growing demand for smart knitwear design with resistive routing paths. The routing network embedded into smart knitwear with conductive knitting stitches is a critical element for connecting different electronic devices, such as textile electrodes, sensors, and heaters. The knitting stitch made with conductive yarn is one of the essential building blocks for textile-based circuitry and controls the power distribution in the wearable electronic knitwear. Knitwear exhibits high flexibility and comfort, making it a good candidate for applications in sports, medicine, and other areas that incorporate electronic devices. Textile-based electronic circuits have become a key element in recent developments in intelligent textiles. Different manufacturing processes for textile-based electronic circuits have been reported, such as embroidery, weaving, printing, and coating. However, few studies have given an analytical equation and a systematic approach to obtaining the equivalent resistance of the conductive knitting stitch network. This paper describes work done to derive analytical equations to model a given resistive network of conductive knitting stitches, built with conductive yarn, and based on the common intarsia knitting and jersey knitting techniques. The experimental results revealed that the derived equations could accurately model the equivalent electrical resistance of conductive stitches of knitwear and could greatly simplify existing models.