(Spotlight on Nanowerk) Next-generation electronic devices will be highly portable, portable, even transplantable, lightweight, and most likely self-powered. Among the various building blocks required for these systems (such as displays, sensors, actuators, etc.), some of the most important components are new flexible data storage systems that have non-volatile capacity, high storage density, high switching speed and reliability endurance properties.
Research groups around the world are focused on studying new flexible memories, which have non-volatile capacity, high density storage, fast switching and reliable endurance property. Organic memories in particular have been seen as the most promising candidates for use in various portable and portable systems in the future due to their remarkable advantages in terms of non-volatile memory characteristics, low cost, ease of manufacture, and ease of manufacture. flexibility.
Flexible non-volatile organic memories are constructed by a variety of device configurations using a variety of material systems. Non-volatile memories can be classified as capacitor type, resistance type and transistor type memories.
Capacitor-based memory (see our previous Spotlight Nanowerk: “Flexible FeRAM Made with CMOS Compatible Approach”) may face the problem of data storage loss due to the simply dielectric intermediate between the upper and lower electrodes. . The most popular structures for organic memory devices that have appeared in the literature so far are resistive type and transistor type.
The memory structure based on resistors (see for example: “Atomristor – memristor effect in atomically thin nanomaterials”) is very simple, it is composed of two low / high crossed electrodes and has a very high memory density.
Transistor memories (read more: “Highly flexible organic flash memory for foldable and disposable electronics”) have certain advantages such as single transistor realization, non-destructive read property and can be integrated with metal Complementary oxide-semiconductor (CMOS) technology.
Various types of materials, including metallic nanoparticles, polymeric materials, ferroelectric materials, small organic molecules, 2D materials, and hybrid composites, have been developed for flexible organic memory device applications.
A recently published review (Small, “Recent Advances in Flexible Data Storage Devices Based on Organic Materials at the Nanoscale”) reviews recent studies and research activities related to flexible data storage devices based on organic materials at the nanoscale. Particular emphasis is placed on organic field effect transistor (OFET) memory with organic semiconductor and flexible resistive memory with organic materials.
In the first part of this review, the authors give a brief introduction to how the data storage system works. The second part is mainly an introduction to the operation of data storage systems. Part three reviews various flexible OFET charge trapping materials. The fourth part concerns flexible resistive memory with organic materials. At the end of their review, the authors describe the challenges and opportunities for the further development of flexible organic memory.
The term Memory is often used to describe a data storage device in the computer system. The conventional storage unit consists of a bistable semiconductor circuit, which can store the byte code. There are many storage units that can form memory cells. Depending on the nature of the storage materials and their different properties, conventional memory devices can be classified into different types, as shown in the figure below.
In their article, the authors focus on elucidating the device structure, memory characteristics, device operating mechanism, and mechanical properties of a series of flexible non-volatile organic memories, from memory. OFET, including floating gate, charge trapping and ferroelectricity. architectures, with organic resistive memory.
They discuss various functional materials including nanoparticles, 2D materials, small molecules, conjugated polymers, organic / inorganic hybrid composites, etc. which have been developed for the memory devices mentioned above on flexible substrates.
In addition, they also discuss the different strategies for manufacturing flexible organic memories.
Although the memory performance of the organic memory device cannot yet compete with that of the silicon-based memory device, organic memories with high density and high switching speed are an important addition in the large semi-memory market. -non-volatile conductors.
Concluding their review, the authors list several challenges that must be addressed before flexible non-volatile organic memory can be applied in practice:
First, the electrical performance must be improved. Second, improve mechanical flexibility and stability: flexibility is the most basic requirement for flexible electronic technology, and it is necessary to achieve the stretching and bending requirements for real products, the performance stability of the device must be maintained when flexible substrates are subjected to a high degree of bending conditions.
Additionally, both organic field effect transistor memory (OFETM) and organic resistive memory (ORM) may face the problems of device-to-device inconsistency and cell non-reproducibility due to the ‘uncertainty of the film microstructure with the manufacturing process of the solution. Higher device efficiency should be achieved for practical applications.
To meet these requirements, close collaborations between various disciplines ranging from chemistry, materials science, physics to electronic engineering are essential, conclude the authors.
Michael is the author of three Royal Society of Chemistry books:
Nano-society: pushing the limits of technology,
Nanotechnology: the future is tiny, and
Nano-engineering: the skills and tools that make technology invisible
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