Efficient organic near-infrared photodetectors based on lead phthalocyanine/C60 heterojunction

• Small molecule near-infrared photodetectors (NIR-PDs) based on a PbPc/C60 planar heterojunction are demonstrated.
• The NIR-PDs show a broad-band response that extends to 1100 nm.
• The optimized NIR-PD exhibits an EQE of 19.7% at 900 nm and a detectivity of 2.34 × 1011 Jones at zero bias.
• The performance is higher than other small molecule NIR-PDs reported.

High efficiency organic small molecule near-infrared photodetectors (NIR-PDs) based on a lead phthalocyanine/C60 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 × 1011 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.

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