Carrier Induced Hopping to Band Conduction in Pentacene
| Autor: | Varsha Rani, Akanksha Sharma, Budhi Singh, Sarita Yadav, Pramod Kumar, Subhasis Ghosh, Nirat Ray |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Materials for devices
Electron mobility Materials science lcsh:Medicine 02 engineering and technology 010402 general chemistry 01 natural sciences Article Pentacene Condensed Matter::Materials Science chemistry.chemical_compound symbols.namesake Phase (matter) Computer Science::Networking and Internet Architecture Thin film lcsh:Science Multidisciplinary Condensed matter physics lcsh:R Fermi level 021001 nanoscience & nanotechnology Thermal conduction 0104 chemical sciences Applied physics Organic semiconductor chemistry symbols lcsh:Q Density functional theory 0210 nano-technology |
| Zdroj: | Scientific Reports Scientific Reports, Vol 9, Iss 1, Pp 1-9 (2019) |
| ISSN: | 2045-2322 |
| Popis: | Charge transport in organic thin films which are generally polycrystalline is typically limited by the localization of the carriers at lattice defects resulting in low carrier mobilities and carriers move from one state to another state by hopping. However, charge transport in organic semiconductors in their single crystalline phase is coherent due to band conduction and mobilities are not limited by disorder resulting in higher carrier mobility. So it is a challenge to enhance the carrier mobility in a thin film which is the preferred choice for all organic devices. Here, we show that it is possible to increase the carrier mobility in polycrystalline thin films by injecting sufficient carriers such that Fermi level can be moved into the region of high density in Gaussian density of states of molecular solids. When the hopping transport happens through the molecular energy levels whose density is low, mobility is decided by incoherent transport however, when the the hopping transport happens through the energy levels with high density, mobility is decided by coherent transport, as in band conduction. We present results highlighting the observation of both band-like and hopping conduction in polycrystalline organic thin films by varying the concentration of injected charge. More importantly the transition from hopping to band transport is reversible. The observed carrier mobilities in both the regimes match well with theoretical estimates of hopping mobility and band mobility determined from first principles density functional theory. |
| Databáze: | OpenAIRE |
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