Novel Electronics for Flexible and Neuromorphic Computing

Abstract

REVIEWbeing converged with artificial intelligence (AI) by providing users' biological and behavioral signals collected in wearable biodevices, [21][22][23][24][25][26][27][28][29][30][31] offering intelligent services based on big data cloud computing and machine learning. [32][33][34][35][36][37][38][39][40] A number of research groups have demonstrated flexible memories, thin film transistors (TFTs), and integrated circuits (ICs) as key technology for data processing, information storage, and communication. [41][42][43][44][45][46][47][48][49] Since Kim et al. [50] reported functional flexible resistive random access memory (RRAM), various chalcogenidebased phase change memories (PCMs) [51][52][53][54] as well as RRAMs using inorganic (e.g., WO 3 , Al 2 O 3 , HfO 2 , TiO 2 ), [45,49,50,[55][56][57] carbon (graphene, carbon nanotubes (CNTs)), [58][59][60][61][62][63][64] and organic materials [65][66][67][68] have been fabricated on polymer films. In addition, an ultrathin TFT and Si-based large-scale integration (LSI) were demonstrated for high-density flexible electronics. [8,69,70] Beyond the front-end device level, flexible packaging has been developed to interconnect core and peripheral modules to realize fully operational system-on-plastic (SoP). [71][72][73][74][75] Neuromorphic computing systems (brain-inspired model of parallel neuron network) are considered as a promising technology for AI applications, overcoming the limitation of von Neumann architecture (serial and iterative processing) for intelligent data analysis and low power consumption. [76][77][78][79][80][81] With the rapid advancement in the electronics (e.g., memristor, PCM, and TFT) on plastics or any type of surface, [82][83][84][85][86][87][88][89][90] emulation of biological synapses (adaptive synaptic weight, [91][92][93][94] and spike-timing-dependent plasticity (STDP) [95][96][97][98][99] of neurons) is being demonstrated on flexible substrate, which realizes an era of merged electronics toward cognitive IoT, physiological sensor, wearable computer, and autonomous driving system. [92,100] Here, we present recent progress in the field of electronics for flexible and neuromorphic applications that can be classified into four main categories: i) various devices (e.g., resistive memory, PCM, TFT, and IC) on plastic for computing, ii) flexible electronic systems using large-scale interconnection and packaging, iii) electronics for neuromorphic engineering, and iv) promising research areas of flexible synaptic applications. In addition, we have organized the main features of the studies in each section as a table to clearly compare their performance and challenges. The new electronic concept of a flexible and Emerging classes of flexible electronic systems that can be attached to a wide range of surfaces from wearable clothes to internal organs have driven significant advances in communication protocols (e.g., Internet of Things, augmented reality) and clinical research, shifting today's personal computing paradigm. The field of "system ...

Organic Solar Cells on Paper Substrates

“…The area of flexible electronics is emerging as the base for launching the next generation pervasive electronics due to the ability to implement electronic systems involving electronic circuits, memories, sensors displays, and photovoltaic cells on light weight, conformal and flexible substrates . The capability of bending, folding, twisting, and stretching a substrate with electronics implemented on it, makes it suitable for various types of innovative and novel applications Flexible electronics may be implemented on various types of flexible substrates including plastics, paper, steel, or textiles—out of these, plastics appear to be the more established substrate and commonly used for flexile electronics today. Synthetic plastic such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polyimide have been successfully used as substrates for the fabrication of flexible and optoelectronic devices because of their lightweight, flexibility, and good mechanical properties …”

2D–Organic Hybrid Heterostructures for Optoelectronic Applications

“…In an effort to realize a high‐performance building block for a neuromorphic computing application, many types of two‐ or three‐terminal synaptic devices have been developed, including memristor, phase‐change memory, resistance switching, ferroelectric memory, floating‐gate memory, and field‐effect transistors, by exploiting oxides, organic materials, and inorganic 2D materials . It should be noted that the above devices and the working principles have been reviewed previously and thus will not be introduced in detail here. Instead, we focus on the current efforts based on organic–inorganic hybrid materials.…”

Micro Light‐Emitting Diodes for Display and Flexible Biomedical Applications

“…Various types of thin‐film µLEDs (e.g., lateral structured µLED, vertical structured µLEDs, and flip chip lateral structured µLED) have been exploited for strategies of enhancing µLED performance . Packaging technology, related to the interconnection of transferred µLEDs to other electronic components and their protection from the external stress, is also crucial for fully functional optoelectronic systems . A number of packaging technologies have been investigated including metal wiring, soldering, flip chip bonding, and anisotropic conductive film (ACF) bonding .…”