Investigating the Limits of PM6:Y6-Based Organic Photodetectors with Ternary Blend Approach

Bulk-heterojunction (BHJ) based organic photodetectors (OPDs) are promising candidates for next-generation flexible photodetectors, owing to their solution processability, mechanical flexibility, and low-cost fabrication. However, the BHJ OPD often suffers from high dark currents, leading to high noise and low detectivity. Here, we report low-noise and highly sensitive binary and ternary blends of OPDs using PM6, Y6, and perylene diimide (PDI). By optimizing the thickness and morphology of the photoactive layer, we reduced the dark current while maintaining light absorption across the range of 300 to 950 nm. The best-performing binary-blend OPD exhibited a dark current density of 14.9 pA/cm 2, responsivity of 0.50 A/W, noise-equivalent power (NEP) of 1.96 × 10 –13 W, and detectivity (D*) of 3.19 × 10 13 Jones. The devices are fast, featuring a −3 dB cutoff frequency of 1.72 MHz and a turn-on response time of 330 ns. The lowest detectable light intensity is ∼798 fW, with a dynamic range of 132 dB. The inclusion of a morphologically and energetically compatible third component with complementary absorption reduced the dark current density by a factor of 10 to 1.72 pA/cm 2 . This led to improved specific detectivity of 9.65 × 10 13 Jones, which is comparable to that of conventional silicon photodetectors, although silicon possesses other superior properties. This work presents a comprehensive strategy designed to significantly enhance the performance of the near-IR OPDs.