Abstract A pressed pellet of unsubstituted palladium (II) phthalocyanine (PdPc) was synthesized and characterized by UV-Vis transmittance and impedance spectroscopy. Optical absorbance analysis revealed that upon increasing the concentration, the absorption at 630 nm became more intense, demonstrating strong aggregation at high concentrations. For the synthesized PdPc pellet, the absorbance decreased beyond 800 nm, and the direct band gap energy was 1.95 eV. The electric properties of the sample were studied for a range of frequency (40–107 Hz) and temperature (300–660 K) using complex impedance analysis. The activation energy and the relaxation time values for both time and frequency ranges were close to each other, suggesting that the electrical conduction and relaxation phenomena were controlled by the same type of charge carrier in the sample. Notably, the sample exhibited a semiconductor–metal transition at temperature TSM = 560 K. The AC-conductance was satisfactorily explained using the Jonscher universal power law. The electrical transport mechanism was dominated by the overlapping large polaron tunneling (OLPT) model. Furthermore, impedance spectroscopy analysis revealed a non-Debye-type relaxation. The Nyquist plot indicates the presence of grains and grain boundary effects. The results demonstrate that this material may be a promising candidate for photovoltaic applications.

中文翻译：

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未取代钯(II)酞菁的电阻抗谱研究

摘要 合成了未取代钯（II）酞菁（PdPc）的压片，并通过紫外-可见光透射率和阻抗光谱对其进行了表征。吸光度分析表明，随着浓度的增加，630 nm 处的吸收变得更加强烈，表明在高浓度下有强烈的聚集。对于合成的 PdPc 颗粒，吸光度下降超过 800 nm，直接带隙能量为 1.95 eV。使用复阻抗分析在频率 (40–107 Hz) 和温度 (300–660 K) 范围内研究样品的电特性。时间和频率范围内的活化能和弛豫时间值彼此接近，表明导电和弛豫现象受样品中相同类型的电荷载流子控制。值得注意的是，样品在 TSM = 560 K 温度下表现出半导体-金属转变。使用 Jonscher 通用幂律可以令人满意地解释交流电导。电传输机制由重叠的大极化子隧穿（OLPT）模型主导。此外，阻抗谱分析揭示了非德拜型弛豫。奈奎斯特图表明存在晶粒和晶界效应。结果表明，这种材料可能是光伏应用的有前途的候选材料。阻抗谱分析揭示了非德拜型弛豫。奈奎斯特图表明存在晶粒和晶界效应。结果表明，这种材料可能是光伏应用的有前途的候选材料。阻抗谱分析揭示了非德拜型弛豫。奈奎斯特图表明存在晶粒和晶界效应。结果表明，这种材料可能是光伏应用的有前途的候选材料。