Efficient organic near-infrared photodetectors based on lead phthalocyanine/C 60 heterojunction

High efficiency organic small molecule near-infrared photodetectors (NIR-PDs) based on a lead phthalocyanine/C-60 planar heterojunction are demonstrated. The NIR-PDs show a broad-band response that extends to 1100 nm. The performance of the NIR-PDs is improved by using CuI as anode buffer layer. The optimized NIR-PD exhibits a response peak at about 900 nm with external quantum efficiencies (EQEs) of 19.7% at zero bias and 35.1% at -6 V, which are higher than other small molecule NIR-PDs reported. Comparable EQEs of 18.0% at zero bias and 33.2% at -6 V are found in the NIR-PD by further using 4,7-diphenyl-1,10-phenanthroline as cathode buffer layer. Meanwhile, the dark current is significantly reduced, which results in a high detectivity of 2.34 x 10(11) Jones at zero bias, which is among the highest detectivities reported for organic small-molecule NIR-PDs. Besides, the NIR-PDs show a reliable stability in ambient condition. (C) 2014 Elsevier B.V. All rights reserved.