Enhanced detectivity of organic photodetectors with a non-conjugated polymer additive

Abstract

Organic photodetectors have attracted increasing attention in the scenario of low-cost imaging, health monitoring, and near-infrared sensing. However, relatively high dark current and trap density block the sensitivity for organic photodetectors. In this manuscript, a simple yet effective strategy is proposed to enhance the detectivity of organic photodetectors by incorporating a non-conjugated polymer additive of polystyrene into the functional layers. Systematic morphological investigation reveals that this strategy can not only enable suppressed amorphous phase but also effectively tune the phase separation in the bulk heterojunction blends. Electrical results suggest the suppressed trap density in optimized organic photodetectors. Consequently, a dark current density of 5.06 × 10−10 A cm−2 is achieved for PM6:Y6-BO-based organic photodetectors, showing a peak detectivity of 6.38 × 1013 cm Hz1/2 W−1 at 850 nm. This strategy is also applicable in various representative organic-semiconductor systems, including PTB7-Th:PC71BM and P3HT:PC61BM blends, superior to other optimization techniques.