A High-Performance Optical Memory Array Based on Inhomogeneity of Organic Semiconductors.
TL;DR: Flexible nonvolatile optical memory devices developed based on the bis[1]benzothieno[3,2-b];2',3'-d']naphtho[2,3-b;6,7-b']dithiophene (BBTNDT) organic field-effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film are revealed.
Abstract: Organic optical memory devices keep attracting intensive interests for diverse optoelectronic applications including optical sensors and memories. Here, flexible nonvolatile optical memory devices are developed based on the bis[1]benzothieno[2,3-d;2',3'-d']naphtho[2,3-b;6,7-b']dithiophene (BBTNDT) organic field-effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film. The devices exhibit average mobility as high as 7.7 cm2 V-1 s-1 , photoresponsivity of 433 A W-1 , and long retention time for more than 6 h with a current ratio larger than 106 . Compared with the standard floating gate memory transistors, the BBTNDT devices can reduce the fabrication complexity, cost, and time. Based on the reasonable performance of the single device on a rigid substrate, the optical memory transistor is further scaled up to a 16 × 16 active matrix array on a flexible substrate with operating voltage less than 3 V, and it is used to map out 2D optical images. The findings reveal the potentials of utilizing [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives as organic semiconductors for high-performance optical memory transistors with a facile structure. A detailed study on the charge trapping mechanism in the derivatives of BTBT materials is also provided, which is closely related to the nanosprouts formed inside the organic active layer.
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TL;DR: A unified model of how charge carriers travel in conjugated polymer films is proposed and it is shown that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolescular aggregation is sufficient for efficient long-range charge transport.
Abstract: Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials.
221 citations
TL;DR: This work focuses on the development of nonvolatile memories and neuromorphic computing systems based on QD thin-film solids and discusses the advantageous traits of QDs for novel and optimized memory techniques in both conventional flash memories and emerging memristors.
Abstract: The continued growth in the demand of data storage and processing has spurred the development of high-performance storage technologies and brain-inspired neuromorphic hardware. Semiconductor quantum dots (QDs) offer an appealing option for these applications since they combine excellent electronic/optical properties and structural stability and can address the requirements of low-cost, large-area, and solution-based manufactured technologies. Here, we focus on the development of nonvolatile memories and neuromorphic computing systems based on QD thin-film solids. We introduce recent advances of QDs and highlight their unique electrical and optical features for designing future electronic devices. We also discuss the advantageous traits of QDs for novel and optimized memory techniques in both conventional flash memories and emerging memristors. Then, we review recent advances in QD-based neuromorphic devices from artificial synapses to light-sensory synaptic platforms. Finally, we highlight major challenges for commercial translation and consider future directions for the postsilicon era.
172 citations
113 citations
TL;DR: This work provides a new guide for developing organic electronics based on natural biomaterials and demonstrates important synaptic functions similar to biological synapses together with a dynamic learning and forgetting process and image-processing function.
Abstract: Inspired by the photosynthesis process of natural plants, multifunctional transistors based on natural biomaterial chlorophyll and organic semiconductors (OSCs) are reported. Functions as photodetectors (PDs) and light-stimulated synaptic transistors (LSSTs) can be switched by gate voltage. As PDs, the devices exhibit ultrahigh photoresponsivity up to 2 × 106 A W-1 , detectivity of 6 × 1015 Jones, and Iphoto /Idark ratio of 2.7 × 106 , which make them among the best reported organic PDs. As LSSTs, important synaptic functions similar to biological synapses are demonstrated, together with a dynamic learning and forgetting process and image-processing function. Significantly, benefiting from the ultrahigh photosensitivity of chlorophyll, the lowest operating voltage and energy consumption of the LSSTs can be 10-5 V and 0.25 fJ, respectively. The devices also exhibit high flexibility and long-term air stability. This work provides a new guide for developing organic electronics based on natural biomaterials.
109 citations
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TL;DR: In this paper, the authors present a platform that makes electronics both virtually unbreakable and imperceptible on polyimide polysilicon elastomers, which can be operated at high temperatures and in aqueous environments.
Abstract: Electronic devices have advanced from their heavy, bulky origins to become smart, mobile appliances. Nevertheless, they remain rigid, which precludes their intimate integration into everyday life. Flexible, textile and stretchable electronics are emerging research areas and may yield mainstream technologies. Rollable and unbreakable backplanes with amorphous silicon field-effect transistors on steel substrates only 3 μm thick have been demonstrated. On polymer substrates, bending radii of 0.1 mm have been achieved in flexible electronic devices. Concurrently, the need for compliant electronics that can not only be flexed but also conform to three-dimensional shapes has emerged. Approaches include the transfer of ultrathin polyimide layers encapsulating silicon CMOS circuits onto pre-stretched elastomers, the use of conductive elastomers integrated with organic field-effect transistors (OFETs) on polyimide islands, and fabrication of OFETs and gold interconnects on elastic substrates to realize pressure, temperature and optical sensors. Here we present a platform that makes electronics both virtually unbreakable and imperceptible. Fabricated directly on ultrathin (1 μm) polymer foils, our electronic circuits are light (3 g m(-2)) and ultraflexible and conform to their ambient, dynamic environment. Organic transistors with an ultra-dense oxide gate dielectric a few nanometres thick formed at room temperature enable sophisticated large-area electronic foils with unprecedented mechanical and environmental stability: they withstand repeated bending to radii of 5 μm and less, can be crumpled like paper, accommodate stretching up to 230% on prestrained elastomers, and can be operated at high temperatures and in aqueous environments. Because manufacturing costs of organic electronics are potentially low, imperceptible electronic foils may be as common in the future as plastic wrap is today. Applications include matrix-addressed tactile sensor foils for health care and monitoring, thin-film heaters, temperature and infrared sensors, displays, and organic solar cells.
2,062 citations
TL;DR: In this article, a unified model of how charge carriers travel in conjugated polymer films is proposed, and it is shown that in high-molecular-weight polymers, efficient charge transport is allowed due to a network of interconnected aggregates that are characterized by short-range order.
Abstract: Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials. The recent demonstration that highly disordered polymer films can transport charges as effectively as polycrystalline semiconductors has called into question the relationship between structural order and mobility in organic materials. It is now shown that, in high-molecular-weight polymers, efficient charge transport is allowed due to a network of interconnected aggregates that are characterized by short-range order.
1,662 citations
TL;DR: This review suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto -electronic switch and memory.
Abstract: While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory.
1,081 citations
TL;DR: The application of organic transistors in the fields of flexible optical displays and microelectronics is reviewed with primary emphasis on the latest developments in the area of active-matrix electrophoretic and organic light-emitting diode displays based on OTFT backplanes.
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569 citations