Near-infrared organic photodetectors with a soluble Alkoxy-Phthalocyanine derivative

The condition of the bulk-heterojunction (BHJ) is an important factor for photodetectors as it significantly influences the efficiency of exciton dissociation from bound exciton pairs inside the active layer. In this study, we realized near-infrared (NIR) photodetectors with the BHJ system of a soluble donor organic semiconductor, 1,4,8,11,15,18,22,25-octaoctyloxy-phthalocyanine, and phenyl-C61-butyric acid methyl ester. By experimenting with the blend ratio of the organic materials, we observed substantial change of device performance owing to the change in the crystalline condition and morphology of the active layer. Our organic photodiodes with optimized BHJ active layer reached shot noise limited specific detectivity of 2.1 x 10(12) Jones and external quantum efficiency of 18% with a bias of-0.5 V at the NIR wavelength of 770 nm. We attributed this improvement to the decrease in grain size inside the BHJ which resulted in an increased exciton dissociation efficiency at the donor-acceptor interface.

Automated summary

The condition of the bulk-heterojunction (BHJ) is crucial for the performance of photodetectors. This study demonstrates the effect of blend ratio on the crystalline condition and morphology of the active layer and observed significant changes in device performance. By optimizing the BHJ active layer, the researchers achieved improved specific detectivity and external quantum efficiency for near-infrared photodetectors.