Near infrared absorbing derivatives of triphenylamine containing 1,1,4,4-tetracyanobutadiene or dicyanoquinodimethane moieties for fast responsive solitary and binary organic photodetectors

Abstract

In this study, the effect of electron-withdrawing electron accepting groups, i.e. 1,1,4,4-tetracyanobutadiene and dicyanoquinodimethane, on the optoelectrical properties of four newly developed derivatives of triphenylamine having methoxy and ethynylbenzene groups is investigated. The molecular structure–property relationships are analyzed from the perspective of potential applications of the compounds as non-fullerene absorbers in near-infrared organic photodetectors. The developed molecular design enables to tune the optical band gaps from 1.24 to 2.0 eV, spanning various red and near-infrared regions. Charge-extracting properties are influenced by various energy levels, with ionization potentials ranging from 5.69 to 6.07 eV and electron affinities varying from 4.07 to 4.74 eV. Either hole or electron mobility values estimated by the tools of time-of-flight and charge carrier extraction by linearly increasing voltage are in the wide range of 8 × 10−6-4.6 × 10−4 cm2 Vs at the electric field of 9.6 × 105 V/cm. The solitary and binary organic photodetectors are fabricated to demonstrate the potential of the compounds for photodetection. The photoresponsivity value of 5.5 × 10−3 A/W and shot-noise-limited specific detectivity of 0.93 × 1011 Jones at 850 nm are achieved using the developed non-fullerene low-molar-mass acceptors as red/near-infrared absorbers. The use of hosts with high hole mobility values decreased the rising and falling times of the photo-responses to under 10 μs in binary organic photodetectors. © 2026 Elsevier B.V.