Shortwave Infrared Organic Photodiodes Realized by Polaron Engineering.

A novel approach for developing shortwave infrared (SWIR) organic photodiodes (OPDs) using doped polymers is presented. SWIR OPDs are challenging to produce because of the limitations in extending the absorption of conjugated molecules and the high dark currents of SWIR-absorbing materials. Herein, we show that the conversion of bound polarons to free polarons by light energy can be utilized as a SWIR photodetection mechanism. To maximize the bound-polaron density and bound-to-free polaron ratio of the doped polymer film, we engineered the doping process and diffused dopant molecules into the crystalline domain of the polymer matrix and confirm a direct correlation between the bound-to-free polaron ratio and device performance. The optimized double-doped SWIR OPD exhibited a high external quantum efficiency of 77100% and specific detectivity of 1.11 × 10 11 Jones against SWIR. These findings demonstrate the application potential of polarons as alternatives for Frenkel excitons in SWIR OPDs. This article is protected by copyright. All rights reserved.