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Organic-inorganic halide perovskite quantum dots (PQDs) constitute an attractive class of materials for many optoelectronic applications. However, their charge transport properties are inferior to materials like graphene. On the other hand, the charge generation efficiency of graphene is too low to be used in many optoelectronic applications. Here, we demonstrate the development of ultrathin phototransistors and photonic synapses using a graphene-PQD (G-PQD) superstructure prepared by growing PQDs directly from a graphene lattice. We show that the G-PQDs superstructure synchronizes efficient charge generation and transport on a single platform. G-PQD phototransistors exhibit excellent responsivity of 1.4 × 10 8 AW –1 and specific detectivity of 4.72 × 10 15 Jones at 430 nm. Moreover, the light-assisted memory effect of these superstructures enables photonic synaptic behavior, where neuromorphic computing is demonstrated by facial recognition with the assistance of machine learning. We anticipate that the G-PQD superstructures will bolster new directions in the development of highly efficient optoelectronic devices. 

The current electric vehicles (EVs) face many challenges like limited charge capacity, low miles/charge, and long charging times. Herein, these issues are addressed by developing a dual‐function supercapacitor‐based energy‐storing carbon fiber reinforced polymer (e‐CFRP) that can store electrical energy and function as the structural component for the EV's body shell. This is achieved by developing a unique design, vertically aligned graphene sheets attached to carbon fiber electrodes on which different metal oxides are deposited to obtain high‐energy density electrodes. A high‐strength multilayer e‐CFRP assembly is fabricated using an alternate layer patterning configuration of epoxy and polyacrylamide gel electrolyte. The e‐CFRP so developed delivers a high areal energy density of 0.31 mWh cm^–2at 0.3 mm thickness and a high tensile strength of 518 MPa, bending strength of 477 MPa, and impact strength of 2666 J m^–1. To show its application in EVs, a toy car's body panel is fabricated with e‐CFRP and the toy car is able to operate using the energy stored in its frame. Moreover, when integrated with a solar cell, this composite powers an Internet of Things device, showing its feasibility in communication satellites.

 

Perovskite solar cells (PSCs) have recently received considerable attention due to the high energy conversion efficiency achieved within a few years of their inception. However, a machine learning (ML) approach to guide the development of high‐performing PSCs is still lacking. In this paper ML is used to optimize material composition, develop design strategies, and predict the performance of PSCs. The ML models are developed using 333 data points selected from about 2000 peer reviewed publications. These models guide the design of new perovskite materials and the development of high‐performing solar cells. Based on ML guidance, new perovskite compositions are experimentally synthesized to test the practicability of the model. The ML model also shows its ability to predict underlying physical phenomena as well as the performance of PSCs. The PSC model matches well with the theoretical prediction by the Shockley and Queisser limit, which is almost impossible for a human to find from an ensemble of data points. Moreover, strategies for developing high‐performing PSCs with different bandgaps are also derived from the model. These findings show that ML is very promising not only for predicting the performance, but also for providing a deeper understanding of the physical phenomena associated with the PSCs.

 

Brain‐inspired (neuromorphic) computing that offers lower energy consumption and parallelism (simultaneous processing and memorizing) compared to von Neumann computing provides excellent opportunities in many computational tasks ranging from image recognition to speech processing. To accomplish neuromorphic computing, highly efficient optoelectronic synapses, which can be the building blocks of optoelectronic neuromorphic computers, are necessary. Currently, carbon nanotubes (CNTs), an attractive candidate to develop circuit‐level photonic synapses, provide weak light responses. The inferior photoresponse of CNTs increases the energy consumption of neuromorphic optoelectronic devices. Herein, a method to grow organic–inorganic halide perovskite quantum dots (PQDs) directly on multiwall CNTs (MWCNTs) to increase the photosensitivity of optoelectronic synapses is demonstrated. The new hybrid material synchronizes the high photoresponse of PQDs and the excellent electrical properties of MWCNTs to provide photonic memory under very low light intensity (125 µW cm⁻²). However, neat MWCNTs do not show any detectable light response at the tested light intensity, as high as 25 mW cm⁻². Since the PQDs are grown directly on and in the MWCNTs, the hybrid PQD‐MWCNT provides a new direction for the future MWCNT‐based optoelectronic devices for neuromorphic computing with a potential to break the von Neumann bottleneck.

 

2D materials have attracted considerable attention due to their exciting optical and electronic properties, and demonstrate immense potential for next‐generation solar cells and other optoelectronic devices. With the scaling trends in photovoltaics moving toward thinner active materials, the atomically thin bodies and high flexibility of 2D materials make them the obvious choice for integration with future‐generation photovoltaic technology. Not only can graphene, with its high transparency and conductivity, be used as the electrodes in solar cells, but also its ambipolar electrical transport enables it to serve as both the anode and the cathode. 2D materials beyond graphene, such as transition‐metal dichalcogenides, are direct‐bandgap semiconductors at the monolayer level, and they can be used as the active layer in ultrathin flexible solar cells. However, since no 2D material has been featured in the roadmap of standard photovoltaic technologies, a proper synergy is still lacking between the recently growing 2D community and the conventional solar community. A comprehensive review on the current state‐of‐the‐art of 2D‐materials‐based solar photovoltaics is presented here so that the recent advances of 2D materials for solar cells can be employed for formulating the future roadmap of various photovoltaic technologies.

 

Wearable electronic devices represent a paradigm change in consumer electronics, on‐body sensing, artificial skins, and wearable communication and entertainment. Because all these electronic devices require energy to operate, wearable energy systems are an integral part of wearable devices. Essentially, the electrodes and other components present in these energy devices should be mechanically strong, flexible, lightweight, and comfortable to the user. Presented here is a critical review of those materials and devices developed for energy conversion and storage applications with an objective to be used in wearable devices. The focus is mainly on the advances made in the field of solar cells, triboelectric generators, Li‐ion batteries, and supercapacitors for wearable device development. As these devices need to be attached/integrated with the fabric, the discussion is limited to devices made in the form of ribbons, filaments, and fibers. Some of the important challenges and future directions to be pursued are also highlighted.

 

The world is recently witnessing an explosive development of novel electronic and optoelectronic devices that demand more‐reliable power sources that combine higher energy density and longer‐term durability. Supercapacitors have become one of the most promising energy‐storage systems, as they present multifold advantages of high power density, fast charging–discharging, and long cyclic stability. However, the intrinsically low energy density inherent to traditional supercapacitors severely limits their widespread applications, triggering researchers to explore new types of supercapacitors with improved performance. Asymmetric supercapacitors (ASCs) assembled using two dissimilar electrode materials offer a distinct advantage of wide operational voltage window, and thereby significantly enhance the energy density. Recent progress made in the field of ASCs is critically reviewed, with the main focus on an extensive survey of the materials developed for ASC electrodes, as well as covering the progress made in the fabrication of ASC devices over the last few decades. Current challenges and a future outlook of the field of ASCs are also discussed.