High-performance UV-Vis-NIR photomultiplier detectors based on titanyl phthalocyanine/squaraine dye bulk heterojunctions†

Abstract

Photodetectors have important applications in science and commerce, but achieving high-performance broad-spectrum detection is still challenging. In this work, a photosensitive composite (Y-TiOPc@SQ1) consisting of Y-type titanyl phthalocyanine (Y-TiOPc) and squaraine (SQ1) was constructed using a bulk heterojunction strategy. Research shows that the photodetector based on Y-TiOPc@0.5%SQ1 (Y-TiOPc@0.5%SQ1-PD) exhibits excellent photodetection properties from 365 nm to 940 nm. At a low intensity of 0.01 mW cm⁻², the external quantum efficiency (EQE) at 365 nm is as high as 12 131%, and the photoresponsivity (R) is 35 683 mA W⁻¹. Compared to Y-TiOPc-PD, it exhibits significant enhancements in the NIR region, with R and EQE increasing by 1.62-fold (700 nm), 1.75-fold (765 nm), 1.69-fold (850 nm), and 2.25-fold (940 nm). In addition, the device exhibits prompt, steady and reproducible photocurrent response curves. Such high performances are attributed to the co-sensitization synergistic coupling enhancement effect between Y-TiOPc NPs and SQ1, the improvement in carrier generation efficiency, separation efficiency and transport rates due to bulk heterojunctions, and the enhancement of external hole tunneling injection efficiency assisted by interfacial trapped electrons. This study demonstrates that the bulk heterojunction strategy based on phthalocyanine and squaraine can effectively improve the performance of photodetectors, offering a novel approach for developing high-sensitivity, wide-spectrum photodetectors.