Current advancements on charge selective contact interfacial layers and electrodes in flexible hybrid perovskite photovoltaics

Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.

Triboelectric nanogenerator for neuromorphic electronics

Building the brain-inspired neural network computing system based neuromorphic electronics is an effective approach to break the von Neumann bottleneck on the hardware level and realize the information processing with high efficiency and low energy consumption in this big data explosion age.Triboelectric nanogenerator(TENG)has two functions of sensing and energy conversion,which promote the application as sensor and/or power supply in self-powered neuromorphic electronics for data storage and biological synapse/neuron behaviors mimicking.This article highlights the relevant works of TENGs for memory devices,artificial synapses and artificial neurons,performs a systematic comparison,and puts forward the future research possibilities and challenges,with the hope of attracting more researchers into this field and promoting the development of TENG based neuromorphic electronics.

Rapid nanomolding of nanotopography on flexible substrates to control muscle cell growth with enhanced maturation

In vivo,multiple biophysical cues provided by highly ordered connective tissues of the extracellular matrix regulate skeletal muscle cells to align in parallel with one another.However,in routine in vitro cell culture environments,these key factors are often missing,which leads to changes in cell behavior.Here,we present a simple strategy for using optical media discs with nanogrooves and other polymer-based substrates nanomolded from the discs to directly culture muscle cells to study their response to the effect of biophysical cues such as nanotopography and substrate stiffness.We extend the range of study of biophysical cues for myoblasts by showing that they can sense ripple sizes as small as a 100 nm width and a 20 nm depth for myotube alignment,which has not been reported previously.The results revealed that nanotopography and substrate stiffness regulated myoblast proliferation and morphology independently,with nanotopographical cues showing a higher effect.These biophysical cues also worked synergistically,and their individual effects on cells were additive;i.e.,by comparing cells grown on different polymerbased substrates(with and without nanogrooves),the cell proliferation rate could be reduced by as much as~29%,and the elongation rate could be increased as much as~116%.Moreover,during myogenesis,muscle cells actively responded to nanotopography and consistently showed increases in fusion and maturation indices of~28%and~21%,respectively.Finally,under electrical stimulation,the contraction amplitude of well-aligned myotubes was found to be almost 3 times greater than that for the cells on a smooth surface,regardless of the substrate stiffness.