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Nam S.,Organic Nanoelectronics Laboratory | Seo J.,Organic Nanoelectronics Laboratory | Park S.,Organic Nanoelectronics Laboratory | Lee S.,Organic Nanoelectronics Laboratory | And 5 more authors.
ACS Applied Materials and Interfaces | Year: 2013

Hybrid phototransistors (HPTRs) were fabricated on glass substrates using organic/inorganic hybrid bulk heterojunction films of p-type poly(3-hexylthiophene) (P3HT) and n-type zinc oxide nanoparticles (ZnO NP). The content of ZnONP was varied up to 50 wt % in order to understand the composition effect of ZnONP on the performance of HPTRs. The morphology and nanostructure of the P3HT:ZnO NP films was examined by employing high resolution electron microscopes and synchrotron radiation grazing angle X-ray diffraction system. The incident light intensity (PIN) was varied up to 43.6 μW/cm2, whereas three major wavelengths (525 nm, 555 nm, 605 nm) corresponded to the optical absorption of P3HT were applied. Results showed that the present HPTRs showed typical p-type transistor performance even though the n-type ZnONP content increased up to 50 wt %. The highest transistor performance was obtained at 50 wt %, whereas the lowest performance was measured at 23 wt % because of the immature bulk heterojunction morphology. The drain current (ID) was proportionally increased with PIN due to the photocurrent generation in addition to the field-effect current. The highest apparent and corrected responsivities (RA = 4.7 A/W and R C = 2.07 A/W) were achieved for the HPTR with the P3HT:ZnO NP film (50 wt % ZnONP) at PIN = 0.27 μW/cm2 (555 nm). © 2013 American Chemical Society.

Seo J.,Organic Nanoelectronics Laboratory | Nam S.,Organic Nanoelectronics Laboratory | Jeong J.,Organic Nanoelectronics Laboratory | Lee C.,Organic Nanoelectronics Laboratory | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2015

We report planar liquid crystal-gated-organic field-effect transistors (LC-g-OFETs) with a simple in-plane drain-source-gate electrode structure, which can be cost-effectively prepared by typical photolithography/etching processes. The LC-g-OFET devices were fabricated by forming the LC layer (4-cyano-4′-pentylbiphenyl, 5CB) on top of the channel layer (poly(3-hexylthiophene), P3HT) that was spin-coated on the patterned indium-tin oxide (ITO)-coated glass substrates. The LC-g-OFET devices showed p-type transistor characteristics, while a current saturation behavior in the output curves was achieved for the 50-150 nm-thick P3HT (channel) layers. A prospective on/off ratio (>1 × 103) was obtained regardless of the P3HT thickness, whereas the resulting hole mobility (0.5-1.1 cm2/(V s)) at a linear regime was dependent on the P3HT thickness. The tilted ordering of 5CB at the LC-P3HT interfaces, which is induced by the gate electric field, has been proposed as a core point of working mechanism for the present LC-g-OFETs. © 2014 American Chemical Society.

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