High-detectivity panchromatic photodetectors for the near infrared region based on a dimeric porphyrin small molecule

Solution processed bulk heterojunction organic photodetectors (OPDs) based on a conjugated dimeric porphyrin small molecule as the donor and PC₇₁BM as the acceptor show a broad and strong spectral response from 300 to 1000 nm. At room temperature and zero bias, the panchromatic OPDs are responsive to the near infrared (NIR) region, exhibiting a very low dark current density of 4.25 × 10^-10 A cm^-2 with a very high external quantum efficiency (EQE) of 48% at 850 nm, leading to a responsivity of 0.33 A W^-1 at 850 nm and detectivity of over 10¹³ Jones from 360 to 950 nm, with a peak detectivity value of 5.73 × 10¹³ Jones at 850 nm. All these parameters are among the best for small molecule NIR OPDs to date, and are comparable to the best NIR OPDs based on polymers, demonstrating the potential of small molecules in panchromatic photodetectors.