The Polymer Society of Korea

Abstract

Vertically stacked image sensors that detect both visible (VIS) and shortwave-infrared (SWIR) light are important for compact multi-spectral imaging. However, current designs often trade off resolution or SWIR sensitivity due to the limits of silicon. Here, we demonstrate a visibly transparent SWIR organic photodiode (OPD) stacked directly on a silicon photodiode for pixel-aligned VIS–SWIR imaging. The OPD uses a new donor polymer, P(BDT-TQ), with strong SWIR absorption and a deep HOMO level, and is optimized with PMMA to improve visible transmittance and reduce traps. The device shows high visible transparency, strong SWIR responsivity, and low dark current. Fully fabricated via low-temperature spin-coating, it is integrated with a 120×64 silicon pixel array using a dual-tap architecture for low-crosstalk dual-wavelength imaging. This scalable, CMOS-compatible design enables compact, high-performance multi-spectral vision systems.