Detectivity enhancement of double-layer organic photodetectors consisting of solution-processed interconnecting layers

A double-layer organic photodetector with solution-processed interconnecting layers composed of a spin-coated ZnOx layer and a spray-coated poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (Poly-TPD) layer is fabricated. The result showed that the double-layer device effectively suppresses the dark current by 2 orders of magnitude, compared to its single layer counterpart. Interestingly, the photocurrent under reverse bias also significantly increased. As a result, the double-layer photodetector showed high on/off ratio of 2.6 × 104 and the detectivity is up to 6.5 × 1012 Jones at −1.5 V. The strategy of spin-coating combining with spray-coating sequentially to form solution-processed interconnecting layers can be an effective and facile way to produce high-detectivity solution-processible organic photodetectors.