Mitigating dark current and improving charge collection for high-performance near-infrared organic photodiodes via p-doping strategy

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 488; p. 151044
• Main Authors: Wang, Yueyue, Gao, Yuanhong, Cao, Shuhan, Wang, Zhenhui, Xu, Meili, Chen, Hong, Yan, Hao, Meng, Hong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-05-2024
• Subjects: Dark current; High-detectivity; Near-infrared photodetector; Organic photodiode; P-doping; Dark current; P-doping; High-detectivity; Near-infrared photodetector; Organic photodiode
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2024.151044

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•A highly sensitive near-infrared organic photodetector is demonstrated by the introduction of a p-doped hole transport layer.•The p-doping strategy leads to an upward shift of the energy levels, which increases the reverse electron injection barrier and charge collection efficiency simultaneously, thus augmenting the external quantum efficiency.•With improved conductivity and reduced trap states, the optimized device exhibits an ultra-low dark current density of 0.13nA cm−2 at −1 V and a highest specific detectivity of 6.02 × 1013 Jones at 800 nm.
Organic photodetectors (OPDs) have gained increasing interest for their remarkable opto-electronic performances and compatibility with flexible devices. However, the commonly occurring high dark current and low detectivity severely reduce the performance and hinder the commercialization of near-infrared photodetectors. Here, we introduce a universal strategy of a p-doped hole transport layer to realize highly sensitive photodetectors. The dark current is significantly reduced by mitigating the reverse charge injection. As a result, the optimized OPD consisting of PM6:Y6 as active layer and 1 nm F4TCNQ p-doped PBTTT as hole transport layer exhibits an ultra-low dark current of 0.13nA cm−2 at −1 V, which is one the best performed near-infrared OPDs ever reported and comparable to commercialized silicon photodetectors. A maximum specific detectivity of 6.02 × 1013 Jones at 800 nm is achieved with improved charge collection efficiency and reduced trap states. The potential commercial application in image sensing is presented by integrating optimized OPDs into high-pixel-density arrays, further demonstrating the significance of the improved detection characteristics in capturing high-quality sample images with this technology. The insights provided in our study have profound implications for the design and optimization of high-performance OPDs spanning the ultraviolet to near-infrared range.