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Abstract Highly crystalline thin films in organic semiconductors are important for applications in high‐performance organic optoelectronics. Here, the effect of grain boundaries on the Hall effect and charge transport properties of organic transistors based on two exemplary benchmark systems is elucidated: (1) solution‐processed blends of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) small molecule and indacenodithiophene‐benzothiadiazole (C16IDT‐BT) conjugated polymer, and (2) large‐area vacuum evaporated polycrystalline thin films of rubrene (C42H28). It is discovered that, despite the high field‐effect mobilities of up to 6 cm2V−1s−1and the evidence of a delocalized band‐like charge transport, the Hall effect in polycrystalline organic transistors is systematically and significantly underdeveloped, with the carrier coherence factor α < 1 (i.e., yields an underestimated Hall mobility and an overestimated carrier density). A model based on capacitively charged grain boundaries explaining this unusual behavior is described. This work significantly advances the understanding of magneto‐transport properties of organic semiconductor thin films.
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The Photo‐Hall Effect in High‐Mobility Organic Semiconductors
Abstract High‐mobility crystalline organic semiconductors are important for applications in advanced organic electronics and photonics. Photogeneration and transport of mobile photocarriers in these materials, although very important, remain underexplored. The photo‐Hall effect can be used to address the fundamental charge transport properties of these functional molecular materials, without the need for fabricating complex transistor devices or chemical doping. Here, a photo‐Hall effect is demonstrated in organic semiconductors, using a benchmark molecular system rubrene as an experimental platform. It is shown that this technique can be used to directly measure the charge carrier mobility and photocarrier density, decouple the surface and bulk transport phenomena, and thus significantly deepen the understanding of the mechanism of photoconductivity in these high‐performance molecular materials.
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- Award ID(s):
- 1806363
- PAR ID:
- 10453488
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 31
- Issue:
- 7
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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