Hybrid Phototransistors Based on Bulk Heterojunction Films of Poly(3-hexylthiophene) and Zinc Oxide Nanoparticle

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 (ZnONP). 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:ZnONP films was examined by employing high resolution electron microscopes and synchrotron radiation grazing angle X-ray diffraction system. The incident light intensity (P-IN) was varied up to 43.6 mu W/cm(2), 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 (I-D) was proportionally increased with P-IN due to the photocurrent generation in addition to the field-effect current. The highest apparent and corrected responsivities (R-A = 4.7 A/W and R-C = 2.07 A/W) were achieved for the HPTR with the P3HT:ZnONP film (50 wt % ZnONP) at P-IN = 0.27 mu W/cm(2) (555 nm).