Iodine-mediated non-destructive multilayer stacking of polymer semiconductors for near-infrared-selective photodiode

Abstract

A facile stacking technology must be developed for various types of polymer semiconductors through a continuous solution process for successful commercial applications of organic electronics. In this study, we report a strategic method of stacking different polymer semiconductors from the same processing solvent in a non-destructive manner using vapor-phase iodine. We utilize the concept of reversible doping mechanism of iodine; interstitial iodine ions in the polymer backbone significantly reduce the solubility of entire films and such an immobilized phase can be quickly recovered to the initial phase via a simple vacuum treatment. Thus, a polymer–polymer p-n planar heterojunction (PHJ) can be realized using the same solvent without compromising the inherent electrical/optical characteristics of the polymer semiconductor. Detailed photophysical and morphological analyses on the doping and dedoping of polymeric semiconductors with iodine are discussed. As a target application of such iodine-mediated non-destructive stacking technology, a thin-film near-infrared(NIR)-selective polymeric photodiode, which can fully reflect the genuine advantages of a well-defined PHJ, is demonstrated. We successfully demonstrate a visible-blind and narrow-band NIR-selective photodiode with a high peak detectivity of 1.50 × 10 11 Jones. © 2019