Toward facile broadband high photoresponse of fullerene based phototransistor from the ultraviolet to the near-infrared region

Organic phototransistor (OPT) is a promising organic device with substantial attention due to its photodetection combined with lightweight, flexibility, large-scale yields, and low cost of organic materials. In addition, spectral tunability and long photocarrier lifetime for organic materials make them highly attractive for advanced optoelectronic device applications. Here, we report high-performance broadband photodetection devices fabricated using an all-organic heterojunction of fullerene/chloroaluminum phthalocyanine with a high-efficiency exciton-dissociation-interface and complementary spectral absorption. Operating at room temperature, the prepared OPTs offer broadband ultraviolet-visible-near infrared spectral response, exhibiting ultrahigh photoresponsivity of 94.4 A/W, the highest detectivity ∼1.5 × 1013 Jones combined with external quantum efficiency of 26,066%, and the ability to measure high-frequency signals. These parameters are comparable or even superior to commercially available silicon carbide, silicon and indium gallium arsenide photodetectors, indicating the possibility of many applications based on broadband detection utilizing our devices. A semi-quantitative calculation and energy level mechanism reasonably explain the ultrahigh performances above. Our results suggest that organic compounds with mutual complementary spectra can be used for constructing photosensitive active layer, in which optimized interfacial electronic structure and morphology help photoexciton dissociation and extend the spectral response range.