Poly(3-hexylthiophene) Band Alignment With SiO2 Determined By Internal Photoemission

ORAL

Abstract

We report band alignment for the widely studied organic semiconductor, Poly(3-hexylthiophene) (P3HT), by using internal photoemission (IPE). P3HT solution was spin coated onto 280 nm thick SiO$_{2}$ on heavily doped P-type silicon. A 10 nm thick aluminum (Al) electrode with adjoining 70 nm thick Al contact pad were deposited onto the P3HT film through aligned shadow masks. Photocurrent in the IPE measurement was generated using a monochromator with photon energy ranging from 1.5eV to 6.0eV (0.05 eV steps) and with a DC voltage which ranged from 20V to -20V (-2V steps) applied between the silicon backside and the thick Al contact. Both positive photocurrent and negative photocurrent were observed. For the IPE measurement, the yield (Y) is defined as the ratio of the carriers contributing to the photocurrent to the incident photon flux, and the threshold at each applied voltage is obtained by extrapolating Y$^{1/3}$(h$\nu )$ to zero. The barrier height is determined from Schottky plots extrapolated to zero field. By using this established method we extract a barrier height of 4.2 eV $\pm$ 0.1 eV for the Si:SiO2 interface and 4.0 eV $\pm$ 0.1 eV for the P3HT:SiO$_{2}$ interface, respectively.

–

Authors

  • Wei Li

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Mary, National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • Xuelei Liang

    Key Laboratory for Physics and Chemistry of Nano Devices, Peking University, Beijing, China

  • James Basham

    The Pennsylvania State University, National Institute of Standards and Technology, National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • Kun Xu

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • Qin Zhang

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • Oleg Kirillov

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • Rusen Yan

    Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA, National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA, NIST; University of Notre Dame

  • Curt Richter

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • Thomas Jackson

    Pennsylvania State University, University Park, PA 16801 USA

  • N.V. Nguyen

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA

  • David Gundlach

    National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Mary, National Institute of Standards and Technology, National Institute of Standards and Technology, Physical Measurement Laboratory, Gaithersburg, Maryland, USA, PML, NIST