Fabrication of High Performance, Narrowband Blue-Selective Polymer Photodiodes with Dialkoxynaphthalene-Based Conjugated Polymer

Abstract

Here, we synthesized a dihexyloxynaphthalene-based conjugated polymer (PNa6-Th) to realize narrowband blue-selective polymer photodiode. The optical, electrochemical, and thermal properties of the synthesized polymer were investigated. It was found that PNa6-Th exhibited a blue-selective absorption with a narrow full width at half-maximum of ∼100 nm and a wide optical band gap of ∼2.52 eV. We constructed a planar heterojunction structure with PNa6-Th and ZnO as a blue-selective electron donor and nonabsorbing acceptor, respectively; To enhance the photodiode performance, a minor amount of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was introduced on the donor layer. By introducing the PCBM on PNa6-Th layer, external quantum efficiency was increased from 5.4% for pristine device to 37.8% for 15 wt % PCBM-doped device, while the dark current values maintained nearly constant. This external quantum efficiency boost leads to high detectivity of 2.31 × 10 12 Jones at −1 V. The physics behind the improved performance were fully discussed based on percolation pathway theory and space-charge-limited current analyses.