Use of additives in porphyrin-tape/C60 near-infrared photodetectors

Abstract: We demonstrate organic heterojunction photodetectors sensitive to wavelengths λ >1500nm based on a solution processed Zn–porphyrin-dimer donor layer that includes phenyl-C61-butyric acid methyl ester (PCBM) and/or 4,4′-bipyridyl (Bipy) additives, and an evaporated C60 acceptor layer. The inclusion of PCBM results in up to a 20-fold increase in differential resistance, while the inclusion of Bipy results in up to a 100% increase in external quantum efficiency (EQE) compared to devices lacking additives. The devices have peak specific detectivities of D ∗ =8.8±0.2×1011 Jones (EQE =3.6±0.1%) at λ =1130nm, and D ∗ =8.2±0.2×1010 Jones (EQE =10.5±0.2%) at λ =1400nm. The maximum external quantum efficiency at λ =1400nm is 13.5±0.3%, approximately double that of previously reported organic near infrared detectors. [Copyright &y& Elsevier]