Preparation of ferroelectric ceramics in a film structure and their photovoltaic properties

Abstract

This paper reports the formation of a newlayered film structure and the highly improved photovoltaic output of the lead lanthanum zirconate titanate (PLZT) employed. The new structural design is described using an upper top transparent indium tin oxide (ITO) electrode. The PLZT film structure exhibited V and lA output. The photovoltaic current of the PLZT film per unit width was more than 10 2 times larger than that of bulk PLZT, while the photovoltaic voltage per unit thickness in the layered film structure was almost the same as that in bulk ceramics and single crystals. These differences are due to the characteristics of the film structure and configuration of the electrode. The PLZT film also has the advantage of easily controllable parameters: film thickness, illuminated area, and illumination intensity. A simple model is used for the phenomenological explanation of the improved photovoltaic effect of the PLZT film.

Constitutive equations for 0-3 polarized PLZT actuators

“…The photo-induced strain and applications of a 0-1 polarized wafer have been studied by a number of authors, e.g., Uchino et al (1985), Fukuda et al (1995) and Shih et al (2005). For a 0-3 polarized PLZT wafer, Ichiki et al (2004Ichiki et al ( , 2005 measured photovoltaic currents and voltages, and then fitted using the least square technique. Qin et al (2007) studied photocurrents of 0-3 polarized wafers.…”

“…The photovoltaic effect shows its merits in a number of aspects: (1) high electrical output voltage, (2) transducer from optical energy to electrical energy, (3) wireless energy transfer, (4) noise elimination vibration control, and (5) remote control. These characteristics are useful in MEMS and MOMS (PoosanaasBurke et al, 1998;Ichiki et al, 2005).…”

“…1(b) has drawn much attention (Ichiki et al, 2005;Qin et al, 2007) since it is easier to fabricate in MEMS and MOMS applications and the 0020-7683/$ -see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijsolstr.2009.08.014 applied voltage for polarization is considerably reduced.…”

“…In an optical actuator, mechanical strain is induced by light illumination, which is referred to as photostriction. Photostrictive phenomena have been found in many materials, e.g., semiconductors (Figielski, 1961;Gauster and Habing, 1967), polymers (Eisenbach, 1980;Charra et al, 1993;Yu et al, 2003;Camacho-Lopez et al, 2004) and ferroelectric ceramics (Fridkin, 1979;Brody, 1983;Poosanaas-Burke et al, 1998;Ichiki et al, 2005). When light illuminates on a semiconductor, it generates free charge carriers due to absorption of photons, which results in mechanical deformation.…”

“…In this type of PLZT wafer, one electrode must be transparent so that light can penetrate the irradiating surface. The transparent electrode can be fabricated by sputtering Indium Tin Oxide (ITO) on the irradiating surface (Ichiki et al, 2005;Leng et al, 2006;Qin et al, 2007).…”