Doping hysteresis effect

Typical CVs for redox switching of ECPs have the shape shown in Figure 18.2 broad peaks are usually obtained while changing the redox state. Reversibility is often not complete (there is a cathodic shift for the reversal peak potential) due to relaxation effects that generate hysteresis phenomena. At last, a plateau characteristic of capacitive behavior is fi equently observed at high doping levels [10-12]. 

The effects of bistability and hysteresis in supertwisted nematic layers were first investigated in [122]. To obtain twist angles larger than 90 , nematics were doped with a small amount of an optically active material. Thus a cholesteric (or chiral nematic) with a large pitch P was created, so that the pitch value had to adjust the boundary conditions for the directors on the substrates. The corresponding texture was first discovered by Grandjean and is discussed in Chapter 6. In 1984 the display based on the Supertwist Birefringent Effect (SBE) was proposed [123]. 

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