Improved Photoresponse of Hybrid ZnO/P3HT Bilayered Photodetector Obtained Through Oriented Growth of ZnO Nanorod Arrays and the Use of Hole Injection Layer

Abstract

We report highly oriented one-dimensional (1-D) growth of zinc oxide (ZnO) nanorod arrays (NRA) which were later utilized to fabricate hybrid photodiodes having the typical photodiode configuration of indium tin oxide (ITO)/ZnO/poly(3-hexylthiophene) (P3HT)/Ag. These functional hybrid bilayered photodiodes were found to have high rectification ratio under dark conditions and demonstrated enhanced responsivity under light illumination. Further, we studied the effect of an intermediate electron blocking layer of poly(ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) on the photodiode characteristics and demonstrated ITO/ZnO/P3HT/PEDOT:PSS/Ag photodiodes, reporting very high rectification ratio and responsivity in this bilayered configuration. The observed results are explained on the basis of the increased surface area of contact between the ZnO nanorods and the P3HT, and also the efficient hole injection into the P3HT layer from the top Ag electrode. © 2015, The Minerals, Metals & Materials Society.