Anomalous photovoltaic effect based on spontaneous polarization of ferroelectric liquid crystals

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Ferroelectric liquid-crystalline (LC) phenylterthiophene derivatives bearing a decenyl group, a disiloxane chain, and a tetracyclosiloxane ring has been synthesized. These compounds exhibit a chiral smectic C (SmC*) phase, where its spontaneous polarization exceeds 100 nCcm-2. The hole mobilities determined by a time-of-flight method were on the order of 1x10-4 cm2V-1s-1. The compound having decenyl group exhibits an anomalous photovoltaic effect in the SmC* phase. It should be noted that even the compound bearing a bulky cyclotetrasiloxane ring exhibit an enatiotropic SmC* phase. The compound bearing a decenyl chain exhibits anomalous photovoltaic effect in the SmC* phase. Under zer-bias, photocurrent in the reversed direction was generated when DC bias was aplied to the sample before light illumination. The polarity of the zero-bias photocurrent was changed by the sign of the DC bias before the illumination.