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 SmTi0.05Cr0.95O3 sample. Analysis shows that localized features of the photogenerated carriers are the reason for the change in bidirectional photosensitive dielectric properties. The optical control of dielectric properties is important for developing non-contact optoelectronic devices. Here, the authors demonstrate a large modulation of the dielectric constant in polycrystalline SmCrO3 by visible light.