Trapped charge-induced pyroelectric-like transient response in single high-resistivity Sb2Se3 nanowires

Dynamic scanning photocurrent microscopy was applied to Sb2Se3 crystalline single nanowires (NWs) to analyze their transient photocurrent responses. These NWs exhibited switching behavior with rapid rise and decay times upon illumination by laser pulses. The estimated spectral responsivity and external quantum efficiency for a freshly‐prepared NW at a bias voltage of 0.3 V and excitation wavelength of 488 nm were ∼16.9 mA/W and ∼42.9%, respectively. A pyroelectric‐like current transient was observed with reduced spectral responsivity when nonpolar Sb2Se3 single‐crystalline NWs were excited by laser pulses. Because Sb2Se3 NWs were nonpyroelectric or ferroelectric, the pyroelectric‐like current could possibly be attributed to temperature dependent nonlinear space‐charge distributions. Defects produced by the external electrical bias generated and re‐distributed space charges in the NWs. As a result, the temperature dependent inhomogeneous electric field led to nonlinear expansions or contractions of the lattice (electrostriction) that can produce pyroelectric current. We obtained a lower bound of equivalent pyroelectric coefficient α ≥ 60.09 μC/m2 K from these materials by fitting the electrical transients. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) Sb2Se3 as a popular thermoelectric material has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. Although Sb2Se3 does not belong to the pyroelectric crystal classes, however, this Letter uncovered an interesting pyroelectric effect induced by nonlinear expansion/contraction of the lattice due to trapped charges in single Sb2Se3 nanowires. The deduced pyroelectric coefficient and responsivity are better than some of the existing pyroelectric and ferroelectric materials.