Wavelength-dependent electrical response of an organic circuit for color sensing without external filters

Abstract

The use of organic semiconductors in photodetectors has led to promising results in low-cost light sensing. Although the relatively narrow absorption band of most organic compounds limits their use as wide-band photodetectors, the selection of materials with the desired spectral properties permits the fabrication of wavelength-selective sensors without external color filters. Here, we present a polymer-gated organic complementary inverter circuit exhibiting wavelength-dependent output voltage change that enables dual color sensing via the use of organic semiconductors (PTCDI-C5 and pentacene) with distinct absorption spectra. When illuminated, the inverter circuit shows a wavelength (color)-dependent output voltage change due to the difference in the spectral properties of the semiconductors. Compared to the dark state, the output voltage of the circuit increases under long-wavelength and decreases under short-wavelength illumination. These findings demonstrate a novel use of photoresponsive organic semiconductors to construct simple dual-color sensitive sensors which may simplify the fabrication of multi-wavelength detector circuits.