Ultra sensitive low-frequency visible light dielectric response measured by real capacitance method

The optical control of dielectric properties is a topic of concern, as it involves the development of new non-contact optoelectronic devices. The bandgap of dielectric materials is generally large, and only high-energy ultraviolet light can modulate the dielectric properties of these materials. Here, we present the Maxwell-Wagner relaxation in polycrystalline SmCrO₃ that can be modulated by visible light. The rate of change of dielectric constant shows negative and then positive change with frequency, with a minimum of −51% at 100 Hz (measure voltage 0.1 Ṽ) and a maximum of +654% peak around 8 kHz. Although Ti-doped SmCrO₃ samples become insulators, visible light can still modulate the appearance of Debye relaxation peaks, and a maximum of +790% ultrasensitive low-frequency photo-dielectric variation was observed in SmTi_0.05Cr_0.95O₃ sample. Analysis shows that localized features of the photogenerated carriers are the reason for the change in bidirectional photosensitive dielectric properties.