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<p>We report the photo-electrical characterization of a halide-perovskite–nematic liquid crystal composite, 1.0 wt% CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3-x</sub>Cl<sub>x</sub> dispersed in an E7 host, in which the central observation is an optically quenchable negative differential resistance (NDR) feature coupled to a three-regime charge-transport profile. The multi-regime charge transport of the resulting ITO/perovskite-NLC/ITO device was investigated through detailed current–voltage (I–V), resistance–voltage (R–V), and conductance-voltage (G–V) measurements across a range of illumination intensities, from dark conditions (0&#xa0;mW/cm<sup>2</sup>) to 100 mW/cm<sup>2</sup>. The composite exhibits a remarkable photoconductive response, with the electrical current increasing by approximately a factor of five and the static resistance decreasing by nearly two orders of magnitude under maximum illumination, confirming the role of the perovskites as an efficient photogeneration center. A detailed analysis of the I-V characteristics reveals a complex, multi-regime charge transport model that is highly dependent on the applied electric field: a low-voltage ohmic region transitions to a bulk-limited, trap-mediated space-charge-limited current (SCLC) regime at intermediate fields, and finally to a Fowler–Nordheim (F–N) tunneling-dominated injection process at high fields. Most significantly, a pronounced negative differential resistance (NDR)-like effect, attributed to field-activated carrier trapping, is observed under dark and low-light conditions. We demonstrate that this NDR phenomenon can be systematically suppressed and ultimately quenched by increasing the incident light intensity. The dual electrical and optical control of the NDR feature, voltage determining the transport regime and illumination determining its magnitude, is the device-level signature of the underlying interfacial chemistry, in which nitrile-anchored mesogens couple director reorientation to the perovskite surface trap distribution, which is a candidate platform for optically programmable switches and resistive memory elements, but the response time and stability metrics needed to assess that potential have yet to be defined.</p>

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Optically-quenched negative differential resistance and multi-regime charge transport in a CH3NH3PbI3-xClx-E7 liquid crystal composite

  • 期刊论文

  • 发表日期：

    2026年6月29日

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  • Ahmet Demir,
  • Ahmad Badreddin Musatat,
  • Kadir Gökşen,
  • Oğuz Köysal

摘要

We report the photo-electrical characterization of a halide-perovskite–nematic liquid crystal composite, 1.0 wt% CH3NH3PbI3-xClx dispersed in an E7 host, in which the central observation is an optically quenchable negative differential resistance (NDR) feature coupled to a three-regime charge-transport profile. The multi-regime charge transport of the resulting ITO/perovskite-NLC/ITO device was investigated through detailed current–voltage (I–V), resistance–voltage (R–V), and conductance-voltage (G–V) measurements across a range of illumination intensities, from dark conditions (0 mW/cm2) to 100 mW/cm2. The composite exhibits a remarkable photoconductive response, with the electrical current increasing by approximately a factor of five and the static resistance decreasing by nearly two orders of magnitude under maximum illumination, confirming the role of the perovskites as an efficient photogeneration center. A detailed analysis of the I-V characteristics reveals a complex, multi-regime charge transport model that is highly dependent on the applied electric field: a low-voltage ohmic region transitions to a bulk-limited, trap-mediated space-charge-limited current (SCLC) regime at intermediate fields, and finally to a Fowler–Nordheim (F–N) tunneling-dominated injection process at high fields. Most significantly, a pronounced negative differential resistance (NDR)-like effect, attributed to field-activated carrier trapping, is observed under dark and low-light conditions. We demonstrate that this NDR phenomenon can be systematically suppressed and ultimately quenched by increasing the incident light intensity. The dual electrical and optical control of the NDR feature, voltage determining the transport regime and illumination determining its magnitude, is the device-level signature of the underlying interfacial chemistry, in which nitrile-anchored mesogens couple director reorientation to the perovskite surface trap distribution, which is a candidate platform for optically programmable switches and resistive memory elements, but the response time and stability metrics needed to assess that potential have yet to be defined.