Dual-functional diffraction grating based on selective metal deposition of photochromic diarylethene

2015

The Chemical Record

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Selective metal-vapor deposition signifies that metal-vapor atoms are deposited on a hard organic surface, but not on a soft (low glass transition temperature, low Tg ) surface. In this paper, we introduce the origin, extension, and applications of selective metal-vapor deposition. An amorphous photochromic diarylethene film shows light-controlled selective metal-vapor deposition, which is caused by a large Tg change based on photoisomerization, but various organic surfaces, including organic crystal and polymers, can be utilized for achieving selective metal-vapor deposition. Various applications of selective metal-vapor deposition, including cathode patterning of organic light-emitting devices, micro-thin-film fuses, multifunctional diffraction gratings, in-plane electrical bistability for memory devices, and metal-vapor integration, have been demonstrated.

Section: Applicationsmentioning

confidence: 99%

Selective Metal-vapor Deposition on Organic Surfaces

2015

The Chemical Record

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“…More density by multilevel recording requires much larger SNR. [45,46] In this article, we report a minute organic memory cell with a micron scale, in which an active memory layer is composed of a DAE-Cu composite film based on selective metal-vapor deposition.One of the major challenges in the field of organic electronics is miniaturization and integration of electrical components. On the other hand, a half-size memory cell with the same SNR easily achieves four-times density.…”

mentioning

confidence: 99%

“…[34,35] An interesting function of DAE is selective metal-vapor deposition. [45,46] In this article, we report a minute organic memory cell with a micron scale, in which an active memory layer is composed of a DAE-Cu composite film based on selective metal-vapor deposition. Selective deposition originates in a large change in a glass transition temperature (T g ) of an amorphous DAE film based on photoisomerization.…”

mentioning

confidence: 99%

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Minute Organic Memory Fabricated by Laser Scanning and Selective Metal‐Vapor Deposition of a Diarylethene–Cu Composite Film

Hoshimoto

2018

Adv Elect Materials

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restricted because, in general, the patterned electrode is fabricated by vacuum evaporation with a shadow mask. It is hard to obtain such a precision mask that can produce micron-level metal patterns; the smallest memory cells that have been obtained so far are around 100 µm. [4,[16][17][18][19][20][21][22][23] Another option for obtaining high memory density is multilevel recording. [24][25][26][27][28] Multilevel recording requires a stable and distinct multilevel between the highest and lowest recording levels and a high signal-to-noise ratio (SNR); in other words, a large difference between the highest and lowest levels, and a small fluctuation in each level. For example, to obtain four-times density (4 bits in a single memory cell), multilevel recording needs 2 4 = 16 distinguishable levels and, therefore, 16-times of an original SNR. More density by multilevel recording requires much larger SNR. In actual organic memory devices reported so far, the level fluctuation is very large, [3,26,[29][30][31][32][33] and it is difficult to obtain enough SNR to achieve multilevel recording. On the other hand, a half-size memory cell with the same SNR easily achieves four-times density. Therefore, reducing memory cell size, or preparing miniaturized electrodes, is very important to obtain high memory density.Photochromism is defined as a reversible change of molecular species and various properties of molecules-aggregation, film, composites, and/or bulk-including a crystal phase are changed as well as color. [34][35][36][37][38][39][40][41] Photochromic diarylethenes (DAEs) are well known as a series of photochromic molecules with very high stability in both isomerization states. [34,35] An interesting function of DAE is selective metal-vapor deposition. [42][43][44] Selective metal-vapor deposition signifies metalvapor atoms deposit on the colored surface generated by UV irradiation onto the DAE film but not on the colorless surface. Selective deposition originates in a large change in a glass transition temperature (T g ) of an amorphous DAE film based on photoisomerization. The core phenomenon of selective deposition is metal atom desorption from a low-T g colorless surface. Selective metal-vapor deposition can be applied to prepare fine metal patterns using maskless vacuum evaporation for electrical and optical devices. [45,46] In this article, we report a minute organic memory cell with a micron scale, in which an active memory layer is composed of a DAE-Cu composite film based on selective metal-vapor deposition.One of the major challenges in the field of organic electronics is miniaturization and integration of electrical components. Such miniaturization, however, has been restricted strictly so far because of the difficulty in fabricating minute electrodes on organic layers and their patterning. The conventional metal electrode has been fabricated generally using vacuum evaporation with a shadow mask, and the resolution of the shadow mask limits the electrode size. In this study, a minute organic memory cell fa...

“…A dual-function grating, which has different diffraction in reflection and transmission, has been constructed using selective metal deposition of DAE [20]. This dual-function grating shows one-dimensional diffraction in transmission and two-dimensional diffraction in reflection, but it was not reprogrammable.…”

mentioning

confidence: 99%

Photoreprogrammable dual-function grating based on photochromism and selective metal deposition

Matsui

2011

Opt. Lett.

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We introduce photoreprogrammable dual-function gratings, which show different diffraction in transmission and reflection. Parallel metal lines on the photochromic diarylethene (DAE) surface were prepared by selective metal deposition, enabling one-dimensional diffraction in transmission and reflection. Then, another isomerization pattern was programmed on the DAE layer by light irradiation. This grating generated unique diffraction: one-dimensional diffraction in the reflection but two-dimensional diffraction in the transmission, and a dual-function grating was achieved. This programmed state on the DAE layer could be erased by UV irradiation and could be reprogrammed to generate different diffraction by visible laser scanning. This result shows the great potential of the photoreprogrammable dual-function grating as a key element in various future optical devices and systems.