Suppressed Trap Density and Reduced Energy Disorder for High-Performance Ultrathin Organic Near-Infrared Photodetectors

Ultrathin Organic Photodetectors (OPDs), renowned for their high miniaturization and energy efficiency, are increasingly integrated into everyday devices, including smartphones, tablet computers, and medical equipment. However, the inherent high trap density and energy disorder associated with organic materials (especially at ultrathin thickness) have posed significant challenges to their performance and efficiency. This study presents a strategy for controlling trap density and energy disorder of high-performance ultrathin near-infrared (NIR) OPDs by incorporating L8-BO into the active layer of PM6:BTP-eC9 blends. A notable increase in trap density is observed as the thickness decreases from 110 to 20 nm, which correlates with a diminished photoelectric response of ultrathin OPDs. The incorporation of L8-BO enhances the crystallinity of the blends, significantly suppressing the trap density and energy disorder. Additionally, the L8-BO strategic integration can mitigate exciton-phonon coupling and extend carrier recombination time. Subsequently, the optimized devices exhibit a responsivity exceeding 0.4 A W-1 and an outstanding specific detectivity (2.30 x 1013 Jones) at 850 nm, positioning them at the forefront of contemporary NIR photodetector technology. These advancements present a significant opportunity to enhance the performance of NIR OPDs, thereby facilitating their integration into the rapidly expanding field.