Both flat-spectrum responsivity and high external quantum efficiency (EQE) of bulk heterojunction organic photodetectors (BHJ OPDs) are greatly in demand and still challenging to realize from the ultraviolet (UV) to near-infrared (NIR) regions. In this article, conjugated polymer donor poly(3-hexylthiophene) (P3HT) and PTB7-Th are blended with a low band gap nonfullerene acceptor (NFA) IEICO-4F to form a ternary BHJ active layer, thereby forming a BHJ OPD with a broadband responsivity spectrum from UV to visible light to NIR region (200–1100 nm). Under 6 V voltage and in the range from 280 to 810 nm, the ternary BHJ OPD shows a relatively flat responsivity spectrum, and the highest responsivity is 1.348 A/W, which is 1.34 times that of the binary BHJ OPD. Specifically, the ternary BHJ OPD achieved the highest EQE at 285 nm and as high as 449.31%. In addition, the ternary OPD detectivity (D*) is 2.65 times that of the binary BHJ OPD. Therefore, ternary BHJ as an active layer provides an effective method to develop BHJ OPDs with an expanded response range, higher responsivity, improved EQE, and broadband spectrum with flat spectral response from the UV to NIR region.
The development of high-efficiency metal-free photocatalysts for eliminating endocrine-disrupting compounds continues to pose a considerable challenge. Herein, we report the rational design and fabrication of a green and efficient donor–acceptor heterojunction photocatalyst, PTQ10:Y6@CSC, via a robust π–π stacking strategy. Relative to the PTQ10:IEICO-4F system with weak π–π interactions, the PTQ10:Y6 heterojunction exhibits a significantly enhanced internal electric field, with an intensity 2.05 times greater. This reinforced internal electric field effectively promotes the dissociation of photogenerated excitons and extends the charge carrier lifetime to 1.473 ns (compared to 1.267 ns for PTQ10:IEICO-4F). As a result, the production efficiency of key reactive species (•O2– and h+) is substantially elevated, enabling the complete degradation of 20 ppm methyltestosterone within 40 min under simulated solar irradiation. The PTQ10:Y6@CSC composite also demonstrates remarkable cycling stability, retaining 97.89% of its initial activity after 16 consecutive runs. Moreover, combining density functional theory simulations with experimental analyses, this study elucidates the underlying photodegradation pathways and reaction mechanisms by identifying the vulnerable attack sites on the methyltestosterone molecule. These findings provide not only a high-performance photocatalytic system for endocrine-disrupting compounds remediation but also fundamental insights into the structure–property relationships governing π–π stacked heterojunctions.
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