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Abstract The physics of charge transport across the interface in an inorganic Si/organic conducting polymer junction diode has received little attention compared to the inorganicp–nsilicon diode. One reason is the amorphous nature of the organic polymer and the polymer chain orientation which introduces disorder and barriers to charge flow. Herein we first present an easy technique to fabricate an inorganic/organic,p-Si/n-poly(benzimidazobenzophenanthroline-BBL) junction diode. The physics of charge transport across the heterojunction, and in the BBL film is then analyzed from the device current-voltage characteristics as a function of temperature in the range 150 K <T< 370 K. The temperature dependence of the diode ideality parameter and of the saturation current density demonstrate that tunneling enhanced charge recombination via exponential trap distributions in the depletion region was responsible for charge transport across the junction. Furthermore, the temperature dependence of the diode conductance revealed that thermal activation and hopping both contributed to charge transport in the BBL film away from the junction. BBL is a ladder polymer with a discrete layered crystal structure that is oriented perpendicular to the substrate. Such polymer chain orientation, combined with a distribution of bond lengths and numerous conjugation paths available for charge delocalization result in the multiple charge transport mechanisms as observed in the diode.
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Temperature dependent charge transport in electrostatically doped poly[benzimidazobenzophenanthroline] thin films
Abstract Charge transport in electrostatically doped poly[benzimidazobenzophenanthroline]‐BBL thin films in a field‐effect transistor geometry were investigated in the temperature range 150 K < T < 370 K. At low temperatures activation and hopping transport mechanisms dominated, while phonon scattering dominated at high temperatures. The activation energies (EA) were found to lie in the range 140 meV < EA < 400 meV implying the existence of deep traps within the polymer bandgap of 1.8 eV. Two quasi‐linear dependencies ofEAon the gate voltage (Vg) were observed withEAdecreasing asVgincreased. An unexpected “metallic‐like” transport characteristic appeared forT > 335 K which depended onVg. Enhanced electron delocalization combined with increased carrier density could be responsible for this “metallic‐like” behavior. Our results show that the existence of deep traps with multiple energy distributions, combined with increased carrier density led to the unusual temperature dependence of charge transport observed in BBL.
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- PAR ID:
- 10390327
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Applied Polymer Science
- Volume:
- 140
- Issue:
- 7
- ISSN:
- 0021-8995
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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