Band bending and Debye screening in F<sub>16</sub>CuPc/BP2T ambipolar organic thin film transistor

H. Ding; Y. Gao; H. Wang; D. Yan

doi:10.1117/12.798962

27 August 2008 Band bending and Debye screening in F₁₆CuPc/BP2T ambipolar organic thin film transistor

H. Ding, Y. Gao, H. Wang, D. Yan

Proceedings Volume 7054, Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics; 70540E (2008) https://doi.org/10.1117/12.798962
Event: Photonic Devices + Applications, 2008, San Diego, California, United States

Abstract

There has been a considerable interest on forming ambipolar organic thin film transistors (OTFTs) because such devices are advantageous for integrated circuits, such as lower power consumption, design and fabrication simplification, and better immunity. Most recently, Shi et al. observed a substantial mobility improvement in ambipolar OTFTs based on the heterojunction formed between copper-hexadecafluoro-phthalocyanine (F₁₆CuPc) and 2,5-bis(4-biphenylyl) bithiophene (BP2T). Specifically, the hole and electron mobility are improved by 3 and 12 folds from the bulk values, respectively. We examined the interface formation between F₁₆CuPc and BP2T using ultraviolet photoemission (UPS) and inverse photoemission spectroscopy (IPES). It is observed that in F₁₆CuPc/BP2T the heterojunction is characterized by band bending in both materials, while in BP2T/F₁₆CuPc the band bending is confined in BP2T only. For F₁₆CuPc/BP2T, the band bending of BP2T and F₁₆CuPc are 0.40 and 0.35 eV, respectively. The band bending region is ~15 nm in both materials, from which the Debye lengths of the materials can be deduced. The combination of the band bending and finite Debye lengths offers an explanation to the observed improvement and thickness dependence of the mobility in OTFTs based on such heterojunctions.

Citation Download Citation

H. Ding, Y. Gao, H. Wang, and D. Yan "Band bending and Debye screening in F₁₆CuPc/BP2T ambipolar organic thin film transistor", Proc. SPIE 7054, Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics, 70540E (27 August 2008); https://doi.org/10.1117/12.798962

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