Electric field-dependent conductivity as probe for charge carrier delocalization and morphology in organic semiconductors
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arXiv
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| Format: | Preprint |
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2025
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| author | Shokrani, Morteza Graf, Felix Maximilian Kompatscher, Anton Derewjanko, Dennis Kemerink, Martijn |
| author_facet | Shokrani, Morteza Graf, Felix Maximilian Kompatscher, Anton Derewjanko, Dennis Kemerink, Martijn |
| contents | The charge carrier localization length α is a crucial, yet often ignored parameter of conjugated polymers that exponentially influences electronic conductivity. Here, we argue it is a unique proxy of the energy landscape as determined by sample morphology and experienced by mobile charges. To determine α, we use that in disordered organic semiconductors, slow thermalization of charge carriers after excitation, e.g. by hopping in a finite electric field, can lead to an effective electronic temperature (T_eff) exceeding the lattice temperature, thereby enhancing conductivity. We experimentally probe this effect by combining temperature- and field-dependent conductivity measurements for a range of representative conjugated polymers, using different dopants, doping protocols and doping concentrations. We find that in the high-field regime (F>1E6V/m), T_eff exhibits distinct trends vs. structural order and doping level, which can be used to extract (effective) localization lengths ranging from ~1nm in fully amorphous systems to over ~10nm in highly ordered polymers. Tight-binding and kinetic Monte Carlo simulations are used to connect measured values to morphological properties and to rule out alternative explanations. Our results demonstrate that finite-field conductivity measurements provide a powerful probe of a characteristic length scale of charge transport that is complementary to conventional structural characterization. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_12310 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Electric field-dependent conductivity as probe for charge carrier delocalization and morphology in organic semiconductors Shokrani, Morteza Graf, Felix Maximilian Kompatscher, Anton Derewjanko, Dennis Kemerink, Martijn Disordered Systems and Neural Networks The charge carrier localization length α is a crucial, yet often ignored parameter of conjugated polymers that exponentially influences electronic conductivity. Here, we argue it is a unique proxy of the energy landscape as determined by sample morphology and experienced by mobile charges. To determine α, we use that in disordered organic semiconductors, slow thermalization of charge carriers after excitation, e.g. by hopping in a finite electric field, can lead to an effective electronic temperature (T_eff) exceeding the lattice temperature, thereby enhancing conductivity. We experimentally probe this effect by combining temperature- and field-dependent conductivity measurements for a range of representative conjugated polymers, using different dopants, doping protocols and doping concentrations. We find that in the high-field regime (F>1E6V/m), T_eff exhibits distinct trends vs. structural order and doping level, which can be used to extract (effective) localization lengths ranging from ~1nm in fully amorphous systems to over ~10nm in highly ordered polymers. Tight-binding and kinetic Monte Carlo simulations are used to connect measured values to morphological properties and to rule out alternative explanations. Our results demonstrate that finite-field conductivity measurements provide a powerful probe of a characteristic length scale of charge transport that is complementary to conventional structural characterization. |
| title | Electric field-dependent conductivity as probe for charge carrier delocalization and morphology in organic semiconductors |
| topic | Disordered Systems and Neural Networks |
| url | https://arxiv.org/abs/2511.12310 |