3D Flexible Laser Sensor From Relaxor Ferroelectric Polymer

Abstract 3D photoelectric devices offer significant advantages over 2D planar photoelectric devices, including the specific ability to detect the direction of incident laser. In this study, a photocapacitor is proposed that utilizes a self‐supported film of relaxor ferroelectric polymer Poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) [P(VDF‐TrFE‐CFE)] and copper (Cu) electrodes. The photocapacitor exhibits a good linear response over a wide spectrum range from 405 to 980 nm due to the photothermal effect of Cu, which results in linear temperature change of the photocapacitor with the laser power. Additionally, P(VDF‐TrFE‐CFE) has a broad dielectric maximum (T_m), with its dielectric constant varying linearly with temperature from the temperature of dielectric maximum up to the melting point. Simultaneously, the dielectric maximum of P(VDF‐TrFE‐CFE) shifts to higher temperatures with increasing frequency, allowing the photocapacitance change to be tunable by adjusting the frequency. This enhances the sensitivity of the photocapacitor to low‐power lasers. Based on its flexibility and ease of processing, a double‐cross laser sensing array is designed, with curved and planar double‐layer cladding and a poly(methylmethacrylate) (PMMA) hemispherical shell. This configuration enables the sensing array to effectively detect wide‐angle laser direction. This work also presents a practical demonstration for 3D photoelectric devices.