Writing-erasing

It is important, however, to realize that whilst many types of chemical species exhibit electro-chromism, only those with favorable electrochromic performance parameters1 are potentially useful in commercial applications. Thus, most applications require electrochromic materials with a high contrast ratio, coloration efficiency, cycle life, and write-erase efficiency.1 Some performance parameters are application dependent displays need low response times, whereas smart windows can tolerate response times of up to several minutes. 

Nicholson and Pizzarello.35"40 Collins and Schiffrin s Lu(Pc)2 was initially studied as a film immersed in aqueous electrolyte, but hydroxide ion from water causes gradual film destruction, attacking nitrogens of the Pc ring.33 Acidic solution allows a greater number of stable write-erase cycles, up to 5 x 106 cycles in sulfuric acid 33 Lu(Pc)2 films in ethylene glycol solution were found to be more stable 34... 

Whilst s-PB, i-PB, PG, and PW are all insoluble in water, PX is slightly soluble in its pure (golden yellow) form (indeed, the electrodeposition technique depends on the solubility of the [FeniFein(CN)6]0 complex). This implies a positive potential limit of about +0.9 V for a high write-erase efficiency in contact with water. Although practical ECDs based on PB have primarily exploited the PB PW transition, this does not rule out the prospect of four-color PB... 

B1536 is a yellow isomer that is converted into a red isomer upon irradiation with 380 nm light. The written data can be erased by irradiation with 543 nm light. This photochromic material (B1536) did not exhibit any apparent fatigue even after 100 write/erase cycles the written data (i.e., the red isomer) were stable at 80°C for more than three months, and thermal back reaction (from the red isomer to the yellow isomer) did not occur even at200°C. ... 

No degradation after repeated write-erase cycles ... 

The results of memory window measurements as a function of writing/erasing pulse amplitude with pulse width of 400 ms are presented in Fig. 1 for both MNS and MNOS structures with and without middle NC layer deposition. Memory window measurements performed by charging pulse width of 100 ms yielded similar results. 

Figure 2.11. Photoinduced birefringence (PIB) in a spin-coated film (200-nm thick) of the MO/poiy(vinyi-A/-methylpyridinium) complex. PIB curves (a) (A, write ON 10 s B, write OFF 30 s C, erasure ON) taken at the same spot after different thermal treatment, (b) Multiple write-erase cycles (25°C write ON 10s, write OFF 30 s, erase ON 30s, erase OFF 10s only the first five of eight identical cycles are shown. Source Zhang et al., 2008. Reprinted with permission from American Chemical Society.

Figure 4. Readout current pulses with the same writing conditions (a) initial readout and (b) after 1.5 billion write/erase cycles. Reprinted with permission from, Liu, C.-Y. Pan, H. L. Fox, M. A. Bard, A.. Chem. Mater. 1997, 9, 1422. 1997 American Chemical Society.

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