Intrinsic Detectivity Limits of Organic Near‐Infrared Photodetectors

Organic photodetectors (OPDs) with a performance comparable to that of conventional inorganic ones have recently been demonstrated for the visible regime. However, near-infrared photodetection has proven to be challenging and, to date, the true potential of organic semiconductors in this spectral range (800-2500 nm) remains largely unexplored. In this work, it is shown that the main factor limiting the specific detectivity (D*) is non-radiative recombination, which is also known to be the main contributor to open-circuit voltage losses. The relation between open-circuit voltage, dark current, and noise current is demonstrated using four bulk-heterojunction devices based on narrow-gap donor polymers. Their maximum achievableD* is calculated alongside a large set of devices to demonstrate an intrinsic upper limit ofD* as a function of the optical gap. It is concluded that OPDs have the potential to be a useful technology up to 2000 nm, given that high external quantum efficiencies can be maintained at these low photon energies. Vandewal, K (corresponding author), UHasselt Hasselt Univ, Inst Mat Res IMO, Agoralaan 1,Bldg D, B-3590 Diepenbeek, Belgium ; IMEC, Associated Lab IMOMEC, Wetenschapspk 1, B-3590 Diepenbeek, Belgium. Armin, A (corresponding author), Swansea Univ, Dept Phys, Singleton Pk, Swansea SA2 8PP, W Glam, Wales. ardalan.armin@swansea.ac.uk; koen.vandewal@uhasselt.be