Carbon Nanotube-Poly(3-Hexylthiophene) Hybrid Thin-Film Phototransistors with Ultra-High Responsively

Phototransistors (PTs) are photodetectors that combine light detection and signal amplification capabilities by modulating the charge-carrier density within the transistor's active channel upon exposure to light.^1–3 Solution-processable phototransistors (PTs) have gained prominence thanks to their outstanding attributes, notably their adaptability to various substrates, including flexible materials, facilitating large-area integration.^4–7Among PTs, hybrid material phototransistors stand out, leveraging the strengths of inorganic materials' high carrier mobility and organic materials' efficient light absorption and tunable bandgap.⁸ This synergy enhances light detection sensitivity and efficiency.^8,9 Conjugated Poly(3-hexylthiophene) (P3HT) and carbon nanotubes (CNTs) are frequently employed in optoelectronics due to P3HT's flexibility, absorption coefficient, and cost-effectiveness, and CNTs' exceptional electrical and optical properties driven by their unique one-dimensional structure.¹⁰In this study, we present a promising solution-processible technique to fabricate a phototransistor utilizing CNTs integrated with P3HT through heterogeneous crystallization as the channel of phototransistor, with the aim of investigating their capabilities in high-responsivity optical detection devices.<br/>Our findings reveal that the devices demonstrate an exceptionally high photoresponsivity of 3.6×10⁵A/W at a wavelength of 470 nm. The exceptional photoresponsivity primarily stems from the high light-absorption characteristics of the conjugated polymer, complemented by the excellent mobility facilitated by the underlying CNT network. Additionally, we determined the device's detectivity by analyzing its noise profile at 10 Hz for various V_GS values. The device’s maximum detectivity reaches approximately 0.9 x 10¹¹, a value that is approximately 5000 times higher than a control sample consisting solely of P3HT at the peak of responsivity. These results show the solution processed P3HT/semi-CNT hybrid platform is a promising approach for advanced photodetection applications.<br/><br/>References:<br/>1.Nam, H. J., Cha, J., Lee, S. H., Yoo, W. J. & Jung, D. Y. A new mussel-inspired polydopamine phototransistor with high photosensitivity: signal amplification and light-controlled switching properties. <i>Chemical Communications</i> <b>50</b>, 1458–1461 (2014).<br/>2.Huang, X., Ji, D., Fuchs, H., Hu, W. & Li, T. Recent Progress in Organic Phototransistors: Semiconductor Materials, Device Structures and Optoelectronic Applications. <i>ChemPhotoChem</i> <b>4</b>, 9–38 (2020).<br/>3.Tavasli, A., Gurunlu, B., Gunturkun, D., Isci, R. & Faraji, S. A Review on Solution-Processed Organic Phototransistors and Their Recent Developments. <i>Electronics 2022, Vol. 11, Page 316</i> <b>11</b>, 316 (2022).<br/>4.Roslan, N. A., Abdullah, S. M., Haliza, W., Majid, A. & Supangat, A. Investigation of VTP:PC 71 BM organic composite as highly responsive organic photodetector. <i>Sensors and Actuators A</i> <b>279</b>, 361–366 (2018).<br/>5. Dou, L., Liu, Y., Hong, Z., Li, G. & Yang, Y. Low-Bandgap Near-IR Conjugated Polymers/Molecules for Organic Electronics. <i>Chem Rev</i> <b>115</b>, 12633–12665 (2015).<br/>6. Park, J. B. <i>et al.</i> Visible-Light-Responsive High-Detectivity Organic Photodetectors with a 1 μm Thick Active Layer. <i>ACS Appl Mater Interfaces</i> <b>10</b>, 38294–38301 (2018).<br/>7.Pace, G. <i>et al.</i> All-Organic and Fully-Printed Semitransparent Photodetectors Based on Narrow Bandgap Conjugated Molecules. <i>Advanced Materials</i> <b>26</b>, 6773–6777 (2014).<br/>8. Zhu, H. <i>et al.</i> Perovskite and conjugated polymer wrapped semiconducting carbon nanotube hybrid films for high-performance transistors and phototransistors. <i>ACS Nano</i> <b>13</b>, 3971–3981 (2019).<br/>9. Chang, P. H. <i>et al.</i> Ultrahigh Responsivity and Detectivity Graphene–Perovskite Hybrid Phototransistors by Sequential Vapor Deposition. <i>Scientific Reports 2017 7:1</i> <b>7</b>, 1–10 (2017).<br/>10.Kufer, D. & Konstantatos, G. Photo-FETs: Phototransistors Enabled by 2D and 0D Nanomaterials. <i>ACS Photonics</i> <b>3</b>, 2197–2210 (2016).